Process for producing long chain N-acyl acidic amino acid

ABSTRACT

A process for producing a long chain N-acyl acidic amino acid removes impurities by separating a mixture composed of a long chain N-acyl acidic amino acid containing an inorganic salt and a medium containing water and tertiary butanol into an aqueous layer and an organic layer containing the long chain N-acyl acidic amino acid at a temperature of from 35 to 80° C.

This application is the national phase under 35 U.S.C. §371 of PCTInternational Application No. PCT/JP99/00730 which has an Internationalfiling date of Feb. 18, 1999, which designated the United States ofAmerica and was not published in English.

TECHNICAL FIELD

The present invention relates to a long chain N-acyl acidic amino acidor a salt thereof, and a simple process for producing the same. Morespecifically, the present invention relates to a long chain N-acylacidic amino acid or a salt thereof, which has substantially no odor andcan be applied even to non-perfume fields, which is diminished in acontent of water soluble impurities such as inorganic salts and reactionby-products of free fatty acid, and which is suitable for the productionof a detergent or a cosmetic composition, wherein the detergent preparedby incorporating it into a liquid detergent causes neither precipitationnor turbidity.

BACKGROUND ART

An amine or alkali metal salt of a long chain N-acyl acidic amino acidhas been extensively used as a surface active agent and an antibacterialagent owing to its surface activity. Particularly, it is extensivelyused in detergents and cosmetic fields such as quasi-drugs andcosmetics, and in many cases comes in direct touch with the human body.Therefore, it is prohibitive to give users an unpleasant feeling. Insuch fields, it is frequently required that final products produce noturbidity, and the odor of the final products has an important value tothe commodity. Therefore, in using the long chain N-acyl acidic aminoacid or a salt thereof in such fields, it is desired to diminishimpurities capable of causing turbidity of the final products and thosecapable of unfavorably affecting the odor of the final products to theutmost.

U.S. Pat. No. 3,758,525 discloses a process for producing a long chainN-acyl acidic amino acid, wherein an acidic amino acid and a long chainfatty acid halide are subjected to condensation reaction in the presenceof an alkali using a mixed solvent of 15 to 80% by volume of ahydrophilic organic solvent and 85 to 20% by volume of water, and afterthe reaction is over, the reaction liquid is adjusted to pH 1, therebyprecipitating a crude crystal of a long chain N-acyl acidic amino acid,which is separated by filtration and washed to remove the hydrophilicorganic solvent, whereby a desired long chain N-acyl acidic amino acidis obtained. However, the long chain N-acyl acidic amino acid obtainedaccording to said process contains inorganic salts because ofinsufficient removal thereof, and moreover, the process for separatingthe long chain N-acyl acidic amino acid as mentioned above is notindustrially advantageous from a viewpoint of equipment and operation.

JP-A 51-13717 discloses a process, wherein a reaction liquid obtained bythe reaction between an acidic amino acid and a long chain fatty acidhalide in a mixed solvent of water and a hydrophilic organic solvent inthe presence of an alkali, is adjusted to pH 1 to 6 using a mineral acidat a temperature of from 40° C. to a boiling point of said hydrophilicorganic solvent, thereby separating into an aqueous layer and an organiclayer containing a desired product, and the hydrophilic solvent is thenremoved from the organic layer to obtain a long chain N-acyl acidicamino acid. However, according to the process, a content of inorganicsalts decreases only to a degree of 1 to 2%, and odoriferous substancesoriginating in the solvent are insufficiently removed. In Examplesthereof, it is specifically disclosed that most of the acetone isremoved from the organic layer by means of vacuum-heating, and then theremaining acetone is removed in a manner such that water is added to theresidue and air is blown to its liquid surface while stirring the liquidat 65° C. However, according to such a solvent removing method asblowing of air to the liquid surface, it is difficult to completelyremove the remaining acetone or remove high boiling odoriferoussubstances mentioned below.

Further, in JP-A 3-284685 of the same applicant as that of U.S. Pat. No.3,758,525 and JP-A 51-13717, acetone and its aldol-condensation productssuch as diacetone alcohol and mesityl oxide are named as substances,which remain in the long chain N-acyl acidic amino acid, and whichcauses an odor in the goods. And it is also disclosed therein that evenwhen the process disclosed in JP-A 51-13717 is used, these odoriferoussubstances cannot be removed completely and as a result, these are leftin the long chain N-acyl acidic amino acid and cause an odor of theproducts. On such a premise, it is further disclosed to remove theseodoriferous substances and salts from an aqueous solution of a salt ofthe long chain N-acyl acidic amino acid by means of reverse osmosismembrane. However, the process is disadvantageous from a viewpoint ofusing an expensive membrane separation apparatus, and it cannot be saidthat the process is simple from an industrial point of view, because theprocess cannot be carried out without complicated operation control suchas control of concentrations and control of membranes.

JP-A 50-5305 discloses that in subjecting an amino acid and a long chainfatty acid halide to condensation in the presence of an alkali, anaqueous lower alcohol is used as a reaction solvent, and as the aqueouslower alcohol, methanol, ethanol, n-propanol, isopropanol, n-butanol,isobutanol and sec-butanol are specifically enumerated in a limitedmanner. However, all the above-mentioned alcohol are primary orsecondary, and therefore in a step of making a pH of the liquid acidic,a dehydration-condensation reaction occurs between the formed long chainN-acyl acidic amino acid and said alcohol solvent, thereby resulting inthe production of an ester. In addition, a dehydration-condensationreaction occurs also between said alcohol solvent and a free fatty acidby product through hydrolysis of the raw material of long chain fattyacid halide, thereby producing an ester. The thus produced ester is acompound which is difficult to separate and remove from the long chainN-acyl acidic amino acid.

JP-A 7-2747 also proposes a separation process using a membrane, whichis, however, disadvantageous like in the process disclosed in JP-A3-284685. In Comparative Example of JP-A 7-2747, it is disclosed todirectly condense the obtained long chain N-acyl acidic aminoacid-containing organic layer, and it is demonstrated that a free fattyacid remarkably increases in the course of said condensing, and thehydrophilic organic solvent is hardly removed.

JP-A 3-279354 discloses a reaction process wherein a mixed solvent ofwater and an hydrophilic organic solvent consisting of acetone andisopropanol is used to prevent the production of odoriferous componentssuch as diacetone alcohol and mesityl oxide, which are greatly producedwhen acetone is used singly as the solvent. There is also disclosed aseparation process wherein the acidified reaction liquid is subjected tocrystallization separation to obtain crystals, which are then dissolvedin a hydrophilic organic solvent, and an aqueous solution of a highconcentration of sodium sulfate is added thereto, thereby separatinginto an organic layer and an aqueous layer. However, according to theprocess, there are left problems such that a step of re-dissolving thecrystals once separated by crystallization is troublesome, it isinevitable for the goods to be contaminated with sodium sulfate as faras a large amount of sodium sulfate is used, and it is inevitable totreat a waste liquid containing a high concentration of sodium sulfate.Moreover, even when the mixed solvent of acetone and isopropanol is usedas the hydrophilic organic solvent, it is not always sufficient todiminish diacetone and mesityl oxide to a degree such that anyadditional removal is not required, and as a result, it is stillessential to remove these odoriferous components. In addition, withrespect to removal of the organic solvent from the organic layer, anExample of said JP-A describes nothing but removal thereof by means ofvacuum-heating as a specific removal means, and only describes a contentof the acetone-condensation product in the long chain N-acyl acidicamino acid is a trace. It is not clear whether or not it is removed to adegree such that it does not affect the odor of the final product.

As mentioned above, a long chain N-acyl acidic amino acid, which hassubstantially no odor and which is diminished in a content of watersoluble impurities such as inorganic salts and free fatty acids isunknown, and a simple process for producing the same is also unknown.

As a result, any long chain N-acyl acidic amino acid or its saltobtained according to a conventional process always has an odor owing toby-products originating from the reaction solvents, and containsimpurities such as inorganic salts and free fatty acids, and thereforethere are left problems such that it cannot be applied to a non-perfumesystem, and when it is incorporated into goods such as a detergent,turbidity or precipitation occurs when stored particularly at a lowtemperature.

DISCLOSURE OF INVENTION

Under these circumstances, it is an object of the present invention toprovide a long chain N-acyl acidic amino acid, which has no effect onperfume of goods, and which has superior stability at low temperature,and it is another object of the present invention to provide a processfor producing the long chain N-acyl acidic amino acid.

Generally speaking, using a mixed solvent of a hydrophilic organicsolvent and water as a reaction solvent, an acidic amino acid and a longchain fatty acid halide are subjected to condensation in the presence ofan alkali to produce a long chain N-acyl acidic amino acid (acylationreaction), and the thus obtained reaction liquid is adjusted to pH 1 to6 to separate into an organic layer and an aqueous layer, therebyobtaining a long chain N-acyl acidic amino acid-containing organic layer(acid-precipitation separation step). However, the obtained long chainN-acyl acidic amino acid is insufficient in removal of inorganic salts.

The present inventors have undertaken extensive studies to solve theproblems of the prior art mentioned above, and as a result, it has beenfound that a mixed liquid of a long chain N-acyl acidic amino acid and amedium containing at least tertiary butanol and water can be separatedinto an aqueous layer and a long chain N-acyl acidic aminoacid-containing organic layer according to the composition of said threecomponents, and thereby inorganic salts remaining in the long chainN-acyl acidic amino acid can be conveyed into the aqueous layer to beremoved (hereinafter the operation being referred to as washing). Thus,tertiary butanol and water are added to the long chain N-acyl acidicamino acid containing inorganic salts to form the three-componentsystem, a composition thereof is appropriately selected, and aseparation-removal treatment is repeatedly carried out, whereby adesired content of inorganic salts can be attained.

The present inventors have further found a fact that said tertiarybutanol used in the above-mentioned washing step can be advantageouslyused as a reaction solvent in the acylation reaction step for theproduction of long chain N-acyl acidic amino acid. In other words, ithas been found that when the acylation reaction is carried out using amixed solvent of tertiary butanol/water, there is observed no productionof odoriferous substances such as aldol-condensation products, which areproduced when a mixed solvent of acetone/water is used as the reactionsolvent as seen in the prior art.

In the case where the obtained long chain N-acyl acidic amino acid isapplied to a surface active agent, it is desired to remove the organicsolvent used for the production of long chain N-acyl acidic amino acidand impurities originated from the organic solvent as far as possible.However, there is a substantial trace quantity thereof remaining. Inpractice, diacetone alcohol and mesityl oxide which seem to originatefrom the acetone solvent can be detected in a now commercially availablelong chain N-acyl acidic amino acid or its salt. As mentioned above, thediacetone alcohol and mesityl oxide even in a trace quantity causes abad odor. In addition, even when these odoriferous substances could beremoved as far as possible, in the resulting long chain N-acyl acidicamino acid or a salt thereof, an odor such as an odor of fatty acidsstill remains, and therefore it is difficult to incorporate intonon-perfume cosmetics or the like.

When tertiary butanol is used as the reaction solvent, anyaldol-condensation products produced when acetone is used are notproduced, and therefore, it is permitted to consider the tertiarybutanol itself only as the odoriferous substance remaining in products.An odor threshold of tertiary butanol is far higher in comparison withthat of the acetone-condensation products such as diacetone alcohol andmesityl oxide, and therefore from a viewpoint of controlling odor, itcan be said that the burden of removal is far less when comparingtertiary butanol with acetone.

Turbidity and precipitation caused when the long chain N-acyl acidicamino acid or its salt is incorporated into a liquid detergent or thelike, and particularly when the incorporated composition liquid isallowed to stand at a low temperature such as about 5° C., are mainlycaused by free fatty acids and inorganic salts contained in the longchain N-acyl acidic amino acid, which are conveyed from the startingmaterials or produced in the course of the production of long chainN-acyl acidic amino acid. Particularly, the free fatty acids can beobtained by decomposition of the long chain N-acyl acidic amino acid,and when once obtained, the free fatty acids can hardly be separatedfrom the long chain N-acyl acidic amino acid or its salt, and thereforeit is important to prevent the yield thereof in the production step. Inthe production step of the long chain N-acyl acidic amino acid, anincrease of the free fatty acids can be observed in a step including athermal history such as removal of a hydrophilic organic solvent bydirectly condensing a long chain N-acyl acidic amino acid-containingorganic layer, as disclosed in the prior art.

This is because a state of the liquid at the time when the solvent isdistillation-removed from the long chain N-acyl acidic aminoacid-containing organic layer is bad, in other words, flowability of theliquid is bad, and moreover the liquid is bubbling and in a veryunstable state.

Usually, in the case where the long chain N-acyl acidic amino acid isseparated from the mixed liquid by distillation-removal of thehydrophilic organic solvent contained in the mixed solvent of water andthe hydrophilic organic solvent, it is usual that the distillation iscarried out under reduced pressure from a viewpoint of heat supply.However, when the distillation-removal of the hydrophilic organicsolvent from the mixed liquid is carried out under reduced pressure, theliquid usually increases its viscosity, and results in a paste havingalmost no flowability. Here, it has been found that thedistillation-removal of the organic substances under such conditions ismarkedly inferior in efficiency, and almost no odoriferous substancesuch as acetone and acetone-condensation products including diacetonealcohol and mesityl oxide can be removed.

As mentioned above, when the distillation-removal of the hydrophilicorganic solvent contained in the mixed solvent of water and thehydrophilic organic solvent is continued to separate the long chainN-acyl acidic amino acid from the mixed liquid, the liquid increases itsconcentration and results in a high viscosity. In order to continue thedistillation while keeping the flowability of the liquid, it isnecessary to raise a temperature of the liquid. Further, to continue thedistillation, it sometimes happens that many dispersed bubbles areproduced in the liquid. In other words, a bubbling state occurs to makethe system very unstable. In such a case, it is necessary to carry outthe distillation taking a great amount of time. For example, thebubbling state is controlled in an intermittent manner such thatpressure of the system is increased or decreased to prohibit bumping, orthe vapor quantity generated is drastically lowered.

Accordingly, in the case where the hydrophilic organic solvent iscondensed to be removed in such a manner, the long chain N-acyl acidicamino acid is greatly subjected to thermal history and then decomposesto produce the decomposition products of free fatty acids. When such asalt of the long chain N-acyl acidic amino acid is incorporated into aliquid detergent, because of the increased free fatty acids in the longchain N-acyl acidic amino acid, a cosmetic composition incorporatedtherewith produces turbidity at a low temperature, and thereby theproperty essential to the product is markedly impaired.

The present inventors have undertaken extensive studies to attainremoval of the hydrophilic organic solvent while preventing the freefatty acid from producing. As a result, it has been found that when theconditions such as a composition of the liquid and a temperature thereofare controlled at the time of removing the hydrophilic organic solventfrom a long chain N-acyl acidic amino acid-containing mixed solution ofwater and the hydrophilic organic solvent, flowability of the liquid indistillation-removal of the solvent can be greatly improved, andviscosity of the liquid during the distillation operation can be keptwithin a favorable range even while keeping a temperature of the liquidlow, and thereby the distillation-removal can be attained to a degree soas to have no effect on an odor of the goods. That is, it is a findingthat in removing the hydrophilic organic solvent from the long chainN-acyl acidic amino acid-containing organic layer, the long chain N-acylacidic amino acid is converted in its alkali salt, and either a solidconcentration of the liquid during distillation is held within a fixedrange under a fixed temperature condition, or a ratio between the longchain N-acyl acidic amino acid and water in the mixed liquid ismaintained within a fixed range under a fixed temperature condition,provided that a composition of the organic solvent in the mixed liquidis not more than 5% by weight.

It is another finding that when the hydrophilic organic solvent isdistillation-removed under the above-mentioned conditions, flowabilityof the liquid can be improved, whereby the liquid temperature ofdistillation is lowered, a thermal history can be greatly avoided, andproduction of the free fatty acids owing to decomposition of the longchain N-acyl acidic amino acid can be substantially prohibited. It is afurther finding that the thus obtained long chain N-acyl acidic aminoacid having a content of the free fatty acid limited to a fixed levelcan exhibit a markedly superior performance. Thereby, the presentinvention has been obtained.

That is, the present invention is as follows.

A process for producing a long chain N-acyl acidic amino acid,characterized by comprising a step (washing step) of removing impuritiesmentioned below by separating a mixture composed of a long chain N-acylacidic amino acid containing an inorganic salt and a medium consistingessentially of water and tertiary butanol into an aqueous layer and anorganic layer containing the long chain N-acyl acidic amino acid at atemperature of from 35 to 80° C.

The above-mentioned process for producing a long chain N-acyl acidicamino acid, wherein the above-mentioned long chain N-acyl acidic aminoacid is obtained through the following steps:

1) a step (acylation reaction step) of subjecting an acidic amino acidand a long chain fatty acid halide to condensation in a mixed solventconsisting essentially of water and tertiary butanol in the presence ofan alkali, and

2) a step (acid-precipitation separation step) of adjusting the pH ofthe obtained reaction liquid to from 1 to 6 with use of a mineral acidto separate into an organic layer and an aqueous layer, therebyobtaining an organic layer containing the long chain N-acyl acidic aminoacid.

The above-mentioned process, wherein the organic layer containing a longchain N-acyl acidic amino acid obtained in the above-mentioned washingstep is subjected to removal of an organic solvent by distillation, inwhich not less than {fraction (1/20)} of carboxyl group of the longchain N-acyl acidic amino acid is converted into its alkali salt, andthe distillation is carried out under conditions that a temperature ofthe resulting mixed liquid is controlled so not to exceed 90° C., andwater is added to maintain a solid concentration of the mixed liquid tofrom 5 to 50% by weight.

The above-mentioned process, wherein the organic layer containing a longchain N-acyl acidic amino acid obtained in the above-mentioned washingstep is subjected to removal of an organic solvent by distillation,which is carried out under conditions that a temperature of the mixedliquid is controlled not to exceed 90° C., and water is added tomaintain a weight ratio between the long chain N-acyl acidic amino acidand water within a range of from 35/65 to 65/35, provided that a contentof the organic solvent in the mixed liquid is not more than 5% byweight.

Further, the present invention provides a long chain N-acyl acidic aminoacid or a salt thereof having a content of an inorganic salt of not morethan 1% by weight, a content of tertiary butanol of from 0.1 to 750 ppmby weight, and/or a content of a free fatty acid of not more than 3.0%by weight, said contents being based on the weight of the long chainN-acyl acidic amino acid. Still further, the present invention providesa detergent or cosmetic composition incorporated with the long chainN-acyl acidic amino acid.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 explains the principle of purification of a long chain N-acylacidic amino acid in accordance with the present invention, and also toshow a composition of causing separation (the region surrounded by aline) among compositions of the above-mentioned amino acid, i.e.N-cocoyl-L-glutamic acid/tertiary butanol/water (in FIG. 1, each scaleappearing on each axis being a weight ratio).

FIG. 2 is to show a schematic view of a spray-evaporating apparatus.

BEST MODE FOR CARRYING OUT THE INVENTION

The process for producing a long chain N-acyl acidic amino acid inaccordance with the present invention has the following steps.

The acylation reaction step in the process in accordance with thepresent invention is a step of subjecting an acidic amino acid and along chain fatty acid halide to condensation in a mixed solvent of waterand a hydrophilic organic solvent (acylation reaction), therebyobtaining a crude long chain N-acyl acidic amino acid. Although thepresent invention is explained with reference to a case where tertiarybutanol is singly used as the most preferred hydrophilic organicsolvent, it is permitted to use tertiary butanol in combination with asmall quantity of a conventional hydrophilic organic solvent such asacetone, methanol, ethanol, propanol, isopropanol, butanol, isobutanol,methyl ethyl ketone, tetrahydrofuran, dioxane and the like in a mannersuch that the effects of the present invention are not injured.

As known, in the water/acetone mixed solvent currently in extensive usefor the condensation reaction between an acidic amino acid and a longchain fatty acid halide, acetone is easily dimerized under either acidicor alkaline conditions to produce diacetone alcohol, which is easilydehydrated under further heating to produce mesityl oxide. In short,aldol condensation products of acetone are produced. These cause a badodor even in trace quantities. For example, in case of a 30 wt % aqueoussolution of a monotriethanolamine salt of long chain N-acyl acidic aminoacid, it is necessary to suppress the content of diacetone alcohol andmesityl oxide in the aqueous solution to several ppm by weight or less.

The present inventors have noticed a lower alcohol used as a non-ketonehydrophilic solvent in which no aldol condensation occurs. In JP-B51-38681, it is disclosed that methanol, ethanol, n-propanol,isopropanol, n-butanol, isobutanol and sec-butanol are used. However,the present inventors have confirmed that in the mixed solvent ofwater/alcohol, under acidic conditions the alcohol easily forms an esterbetween the acylation reaction product of the long chain N-acyl acidicamino acid and the long chain fatty acid halide, which is as disclosedalso in JP-A 7-2747. Notwithstanding, it has been surprisingly foundthat no ester as mentioned above is produced and no production of otherimpurities is observed, when as the reaction solvent, the mixed solventof water/tertiary butanol is used under the conditions defined in thepresent invention.

From the facts mentioned above, it has been made clear that when themixed solvent of water/tertiary butanol is used as the acylationreaction solvent, neither aldol condensation products even in a tracequantity causing a bad odor like in a ketone, nor ester between the longchain N-acyl acidic amino acid and the long chain fatty acid halide likein a primary or secondary alcohol is produced.

In the organic layer obtained in the acid-precipitation separation stepthrough the acylation step, an inorganic salt still remains to an extentsuch that it should be removed. For example, JP-A 51-13717 discloses inits Example that the long chain N-acyl acidic amino acid obtainedthrough distillation-removal of the organic solvent from the organiclayer contains an inorganic salt in an amount as large as 1 to 2%. Whenthe long chain N-acyl acidic amino acid containing such a large amountof the inorganic salt is converted, for example, into a 30 wt % aqueoussolution of a triethanolamine salt thereof, the turbidity is remarkableat a low temperature, and sometimes precipitation occurs. With respectto the long chain N-acyl acidic amino acid or its salt in accordancewith the present invention, a content of inorganic salts is not morethan 1% by weight, preferably not more than 0.5% by weight, morepreferably not more than 0.1% by weight, based on the weight of the longchain N-acyl acidic amino acid.

When the mixed solvent of water/tertiary butanol is used as the reactionsolvent, a further advantage can be observed. In the case where themixed solvent of water/acetone is used and the acetone recovered fromthe reaction mixture is reused, for example, the acetone distilled fromthe organic layer is reused, as mentioned previously, and rectificationis required to separate acetone from the aldol condensation products.Whereas, when tertiary butanol is used, the tertiary butanol distilledfrom the organic layer can be used as is, because such impuritiesmentioned above are not produced. It is advantageous from a viewpoint ofeliminating a process step.

In addition, tertiary butanol can give an advantage also from aviewpoint of handling thereof. When the rectification for the purpose ofseparating the aldol condensation products is carried out in order torecover and reuse acetone, it is necessary to recover high purityacetone having a substantially low water content. Such acetone hassevere inflammability and combustibility and easily forms a combustiblegas with air, and therefore it is necessary to take care of its storingand handling on reuse. On the contrary, tertiary butanol forms anazeotrope with water, and therefore in recovering and reusing it, it isimpossible to condense tertiary butanol to a degree of a weight ratio ofmore than tertiary butanol/water=85/15. Thus, tertiary butanol ishandled in a state such that a water content is always more than 15% byweight, and therefore easier in storing and handling as compared withacetone.

When the mixed solvent of water/tertiary butanol is used as the reactionsolvent, there can be given a further great advantage. That is, when themixed solvent of water/tertiary butanol is used as the reaction solvent,it is only necessary to add water and/or tertiary butanol to the organiclayer obtained through the acid-precipitation separation to adjust acomposition of long chain N-acyl acidic amino acid/tertiarybutanol/water within a pre-determined range, whereby the organic layercan be separated into an aqueous layer and an organic layer to removethe inorganic salt present in the foregoing organic layer.

On the other hand, in the case of reaction in the mixed solvent ofwater/acetone, two-phase separation of the organic layer obtainedthrough the acid-precipitation separation into an organic layer and anaqueous layer has never been found regardless of any variations in theorganic layer composition or the liquid temperature. While, the reasonwhy in the solvent system of water/acetone, a two-phase separation intothe organic layer and the aqueous layer can be seen in theacid-precipitation separation, seems due to a salting out effect of alarge amount of inorganic salts such as NaCl and Na₂SO₄. Therefore, whenthe mixed solvent of water/acetone is used, it is indispensable to carryout a process wherein a high concentration of sodium sulfate is added inorder to accomplish the separation washing of the organic layer, asdisclosed in JP-A 3-279354. In such a case, many salts inevitably remaintherein.

From the organic layer obtained by separating into the aqueous layer andthe organic layer, tertiary butanol is removed to obtain the long chainN-acyl acidic amino acid. When the long chain N-acyl acidic amino acidor its salt is used for a surface active agent or the like, it isdesired to remove the tertiary butanol as far as possible in aconventional manner such as distillation, but it inevitably remains in atrace quantity. In the commercially available long chain N-acyl acidicamino acid or its salt, diacetone alcohol and mesityl oxide, probablyoriginating from the acetone solvent, can be detected. The unremoveddiacetone alcohol and the mesityl oxide cause a bad odor. On thecontrary, it has been found that tertiary butanol remaining in a traceamount can serve for masking a fatty acid like odor peculiar to the longchain N-acyl acidic amino acid or its salt. Recently, in the fields ofcosmetics or the like, there is a tendency of non-perfumed products, andin such a case, materials to be blended are required to have no odor. Sofar, even when the diacetone alcohol and the mesityl oxide are removedas far as possible, it is impossible to free the long chain N-acylacidic amino acid or its salt from any odor, and therefore there is lefta problem unsolved when it is incorporated into non-perfume cosmetics.

Tertiary butanol itself has a high odor threshold. For example, in thecase of a 30% by weight aqueous solution of monotriethanolamineN-cocoyl-L-glutamate, which is one of the long chain N-acyl acidic aminoacids, the odor threshold thereof is 150 ppm by weight in said aqueoussolution. In other words, a tertiary butanol content in this casecorresponds to 750 ppm by weight based on the weight of ofN-cocoyl-L-glutamic acid. In the present invention, a content of thetertiary butanol serving for masking the fatty acid like odor of theN-acyl acidic amino acid is from 0.1 to 750 ppm by weight, preferablyfrom 0.1 to 300 ppm by weight, more preferably from 0.1 to 150 ppm byweight, based on the weight of the N-acyl acidic amino acid.

In terms of the 30% by weight aqueous solution of themonotriethanolamine salt, the above-mentioned numerical values arereplaced by from 0.02 to 150 ppm by weight, from 0.02 to 60 ppm byweight, and from 0.02 to 30 ppm by weight, respectively. Thus, saidaqueous solution has substantially no odor. This is greatly advantageousfrom an industrial point of view.

The acidic amino acid used as a material in the process in accordancewith the present invention is a monoamino dicarboxylic acid having twocarboxyl groups and one amino group in the molecule, and the amino groupmay be substituted with methyl or ethyl to be expressed as N-methyl andN-ethyl. The acidic amino acid includes its optical isomers such asD-isomer, L-isomer and racemic modification. Examples thereof areglutamic acid, aspartic acid, lanthionine, β-methyllanthionine,cystathionine, djenkolic acid, felinine, aminomalonic acid,β-oxyaspartic acid, α-amino-α-methylsuccinic acid, β-oxyglutamic acid,γ-oxyglutamic acid, γ-methylglutamic acid, γ-methyleneglutamic acid,γ-methyl-γ-oxyglutamic acid, α-aminoadipic acid, α-amino-γ-oxyadipicacid, α-aminopimelic acid, α-amino-γ-oxypimelic acid, β-aminopimelicacid, α-aminosuberic acid, α-aminosebacic acid and pantothenic acid.When subjected to acylation reaction, these may be its alkali metal saltand its amine salt.

Preferred examples of the long chain fatty acid halide used as amaterial in the process in accordance with the present invention areacid chlorides of saturated or unsaturated fatty acids having 8 to 20carbon atoms, acid bromides thereof and acid iodides thereof, which maybe straight, branched or cyclic. Specific examples thereof are halidesof straight fatty acids such as caprylic acid, pelargonic acid, capricacid, undecanoic acid, lauric acid, tridecanoic acid, myristic acid,pentadecanoic acid, palmitic acid, margaric acid, stearic acid,nonadecanoic acid and arachic acid; halides of branched fatty acids suchas 2-butyl-5-methylpentanoic acid, 2-isobutyl-5-methylpentanoic acid,dimethylocatanoic acid, dimethylnonanoic acid, 2-butyl-5-methylhexanoicacid, methylundecanoic acid, dimethyldecanoic acid,2-ethyl-3-methylnonanoic acid, 2,2-dimethyl-4-ethyloctanoic acid,methyldocosanoic acid, 2-propyl-3-methylnonanoic acid, methyltridecanoicacid, dimethyldodecanoic acid, 2-butyl-3-methylnonanoic acid,methyltetradecanoic acid, ethyltridecanoic acid, propyldodecanoic acid,butylundecanoic acid, pentyldecanoic acid, hexylnonanoic acid,2-(3-methylbutyl)-3-methylnonanoic acid,2-(2-methylbutyl)-3-methylnonanoic acid, butylethylnonanoic acid,methylpentadecanoic acid, ethyltetradecanoic acid, propyltridecanoicacid, butyldodecanoic acid, pentylundecanoic acid, hexyldecanoic acid,heptylnonanoic acid, dimethyltetradecanoic acid, butylpentylheptanoicacid, trimethyltridecanoic acid, methylhexadecanoic acid,ethylpentadecanoic acid, propyltetradecanoic acid, butyltridecanoicacid, pentyldodecanoic acid, hexylundecanoic acid, heptyldecanoic acid,methylheptylnonanoic acid, dipentylheptanoic acid, methylheptadecanoicacid, ethylhexadecanoic acid, ehtylhexadecanoic acid,propylpentadecanoic acid, butyltetradecanoic acid, pentyltridecanoicacid, hexyldodecanoic acid, heptylundecanoic acid, octyldecanoic acid,dimethylhexadecanoic acid, methyloctylnonanoic acid, methyloctadecanoicacid, ethylheptadecanoic acid, dimethylheptadecanoic acid,methyloctyldecanoic acid, methylnonadecanoic acid, methylnonadecanoicacid, dimethyloctadecanoic acid and butylheptylnonanoic acid; halides ofstraight mono-enoic acids such as octenoic acid, nonenoic acid, decenoicacid, caproleic acid, undecylenic acid, linderic acid, obtusilic acid,laurolenoic acid, tridecenoic acid, tsuzuic acid, myristoleic acid,pentadecenoic acid, hexadecenoic acid, palmitoleic acid, heptadecenoicacid, octadecenoic acid, oleic acid, nonadecenoic acid and gondoic acid;halides of branched mono-enoic acids such as methylheptenoic acid,methylnonenoic acid, methylundecenoic acid, dimethyldecenoic acid,methyldodecenoic acid, methyltridecenoic acid, dimethyldodecenoic acid,dimethyltridecenoic acid, methyloctadecenoic acid, dimethylheptadecenoicacid and ethyloctadecenoic acid; halides of di- or tri-enoic acids suchas linoleic acid, linielaidic acid, eleostearic acid, linolenic acid,linolenelaidic acid, pseudoeleostearic acid, parinaric acid andarachidonic acid; halides of acetylenic acids such as octynoic acid,nonynoic acid, decynoic acid, undecynoic acid, dodecynoic acid,tridecynoic acid, tetradecynoic acid, pentadecynoic acid, heptadecynoicacid, octadecynoic acid, nonadecynoic acid and dimethylocatadecynoicacid; and halides of cyclic acids such as methylene-octadecenoic acid,methyleneoctadecanoic acid, aleprolic acid, aleprestic acid, aleprylicacid, alepric acid, hydnocarpic acid, chaulmoogric acid, gorlic acid,α-cyclopentylic acid, α-cyclohexylic acid, α-cyclopentylethylic acid.The long chain fatty acid halide usable for the process in accordancewith the present invention includes halides of fatty acids derived fromnatural fat and oil, provided that the halides are those of a mixedfatty acid containing not less than 80% of the above-mentioned saturatedor unsaturated fatty acid having 8 to 20 carbon atoms. For example,there are enumerated halides of coconut oil fatty acid, palm oil fattyacid, palm kernel oil fatty acid, corn oil fatty acid, peanut oil fattyacid, cottonseed oil fatty acid, linseed oil fatty acid, sunflower oilfatty acid, soybean oil fatty acid, sesame oil fatty acid, caster oilfatty acid, olive oil fatty acid, tsubaki oil fatty acid, tallow oilfatty acid, hardened tallow oil fatty acid, lard oil fatty acid, milkoil fatty acid and fish oil fatty acid. The smaller a free fatty acidcontent in the long chain fatty acid halide, the better.

A molar ratio of long chain fatty acid halide/acidic amino acid is notmore than 1.05, preferably not more than 1.0, more preferably not morethan 0.98. When the ratio exceeds 1.0, the fatty acid halide issubjected to hydrolysis, thereby producing the free fatty acid.

The tertiary butanol used as the reaction solvent for the acylationreaction step in the process in accordance with the present inventionneed not have a high purity, and therefore it is permitted to use thosecontaining water or those which are recovered from a reaction system andwhich are not rectified. A mixing ratio of water/tertiary butanol at thetime of the reaction is preferably within a range of from 85/15 to 20/80by volume.

A concentration of the acidic amino acid to be fed for the acylationreaction step in the process in accordance with the present invention isnot particularly limited. However, a viscosity of the reaction liquidincreases during the reaction according to the lapse of time, andtherefore the feeding concentration should be controlled so as to enableto stir and mix the system even at the time close to completion of thereaction.

As the alkali substances used for the acylation reaction step inaccordance with the present invention, for example, there are inorganicbases such as sodium hydroxide, potassium hydroxide, calcium hydroxideand barium hydroxide. It is recommended to maintain the pH during thereaction from 9 to 13.5, preferably from 10 to 13. When the pH is lessthan 9, the long chain fatty acid halide is hard to react with theacidic amino acid, thereby increase the free fatty acid caused byhydrolysis. When the pH exceeds 13.5, substantially no disadvantages arebrought about. However, it is not recommendable from a viewpoint ofnatural resources, because the amount of alkali is unnecessarilyincreased with an increase in the amount of an acid consumed in thesuccessive acid-precipitation separation step.

A reaction temperature of the acylation reaction step in the process inaccordance with the present invention is not particularly limited.Generally speaking, the reaction temperature can be advantageouslylowered with decrease in a production ratio of free fatty acid. However,when the temperature is too low, in the course of the reaction, eitherviscosity of the reaction liquid is made too high to enable to stir, orit happens that produced materials precipitate, depending upon a kind ofthe produced long chain N-acyl acidic amino acid or a concentrationthereof in the reaction liquid. Therefore, the temperature should becontrolled so as not to meet with such disadvantages. It is permitted tochange the reaction temperature during the reaction according to thelapse of time. The acylation reaction temperature is usually within arange of from −10 to 70° C., preferably within a range of from −10 to20° C., more preferably within a range of from −5 to 10° C.

The acylation reaction step in the process in accordance with thepresent invention can be carried out in a semi-batch manner, wherein theacidic amino acid, alkali and reaction solvent in respectivepredetermined amounts are fed in a stirring vessel, and thereafter thelong chain fatty acid halide is continuously fed therein together withan alkali to make the pH thereof alkaline, or in a manner such that thereaction solvent is fed therein, and thereafter an aqueous alkalisolution of the acidic amino acid and the long chain fatty acid halideare continuously fed therein at the same time. After a predetermineddegree of the reaction is over, the liquid in the stirring vessel issubjected to the successive acid-precipitation separation step. Infeeding the long chain fatty acid halide into the stirring vessel, itmay be sprayed or fed so as to be introduced into the liquid.Alternatively, it may be carried out in a continuous manner, whereinusing the stirring vessel or a tubular reactor, the reaction solvent,the aqueous alkali solution of the acidic amino acid and the long chainfatty acid halide are continuously fed therein, while continuouslytaking out the reaction liquid, which is then subjected to thesuccessive acid-precipitation separation.

In the process in accordance with the present invention, it is importantto conduct the condensation reaction between the acidic amino acid andthe long chain fatty acid halide under stirring or under a conditionthat liquids are sufficiently mixed. Under an insufficient stirringcondition, selectivity of the condensation reaction between the acidicamino acid and the long chain fatty acid halide is lowered to increase aproduction of the free fatty acid owing to hydrolysis of the long chainfatty acid halide. With respect to the reason thereof, it seems that thereaction system forms two phases, the reaction proceeds at an interfaceof the long chain fatty acid halide dispersed in the liquid, andtherefore renewal of the interface is essential for maintaining thereaction selectivity.

The stirring is carried out necessarily under not less than 0.2 kW/m³ interms of a stirring power. Even under a stirring power lower than that,it is possible to obtain the long chain N-acyl acidic amino acid, but itis not sufficient to obtain the long chain N-acyl acidic amino acidhaving a content of the free fatty acid of not more than 3% by weight,which is one embodiment of the present invention. The stirring power ispreferably not less than 0.3 kW/m³, more preferably not less than 0.5kW/m³.

The acid-precipitation separation step in the process in accordance withthe present invention is a step of adjusting the acylation reactionliquid to pH 1 to 6 using a mineral acid such as hydrochloric acid andsulfuric acid, thereby separating it into two layers of an organic layerand an aqueous layer to obtain the desired organic layer. In theacylation reaction liquid, the produced long chain N-acyl acidic aminoacid exists in the form of its alkali salt. By adding a mineral acidthereto, a part or the whole of the carboxyl group appended to the longchain N-acyl acidic amino acid is converted to a free acid, and at thesame time the reaction liquid is separated into an organic layer and anaqueous layer.

The pH at the time of the acid-precipitation separation can be changedwith change of dissociation condition of the carboxyl group, accordingto which the separation condition, namely a weight ratio between theorganic layer and the aqueous layer, and a removing degree of theinorganic salts are changed, and therefore it is recommended to carryout the acid-precipitation separation step preferably at pH 1 to 3, morepreferably at pH 1 to 2.5.

A temperature of the acid-precipitation separation is from 35° C. to aboiling point of the hydrophilic organic solvent, for example, 80° C.when the hydrophilic organic solvent is tertiary butanol. Preferably, itis from 40 to 70° C. When the temperature is lower than 35° C., the timebefore reaching a separation equilibrium may be prolonged, or aremarkable amount of the inorganic salt remains in the organic layereven at a stage of the equilibrium, or no separation occurs dependingupon a kind of the long chain N-acyl acidic amino acid or itsconcentration in the liquid. A boiling point of the azeotropiccomposition of water/tertiary butanol is about 80° C. under atmosphericpressure, and at a temperature exceeding 80° C., boiling occurs, and asa result it becomes necessary to carry out the separation underincreased pressure. This is disadvantageous, because a specificapparatus is required.

The washing step in the process in accordance with the present inventionis a step of conveying water soluble impurities present in the organiclayer obtained in the acid-precipitation separation step to an aqueouslayer by means of liquid-liquid extraction, thereby reducing theimpurities. More specifically, to the organic layer acid-precipitationseparated, water and/or tertiary butanol are(is) added to adjust acomposition of long chain N-acyl acidic amino acid/tertiarybutanol/water, whereby the water soluble impurities in the organiclayer, mainly inorganic salts produced during the reaction and in theacid-precipitation separation step, are conveyed to an aqueous layerthrough the liquid-liquid extraction.

At this time, respective concentrations of the foregoing threecomponents are adjusted so as to make the long chain N-acyl acidic aminoacid from 0.001 to 55% by weight, tertiary butanol from 5 to 45% byweight and water from 20 to 99% by weight, thereby causing theseparation. By making good use of such a liquid separation, it ispossible to remove the inorganic salts remaining in the long chainN-acyl acidic amino acid-containing organic layer.

Behavior of the separation is expressed as an example with reference toa triangular coordinate relating to a composition (% by weight) ofN-cocoyl-L-glutamic acid/tertiary butanol/water, wherein a compositioncapable of causing the separation is a region surrounded by line in FIG.1 (separation region).

As far as the composition is within such a region, the mixed liquid canbe separated into two layers of the N-cocoyl-L-glutamic acid-containingorganic layer and an aqueous layer. Therefore, when respectivecompositions are determined so as to enter within such a region,purification of the organic layer can be conducted many times. Forexample, the purification can be repeated until a content of theinorganic salts in the organic layer reaches a desired degree. This isillustrated in more detail with reference to an example of FIG. 1

The scale appearing on each axis is a weight ratio. When a compositionof an organic layer after the acid-precipitation separation isdesignated with Point A, water is added to obtain a compositiondesignated with Point B, whereby the above-mentioned organic layer isseparated into an organic layer and an aqueous layer, whose compositionsare designated with Point C and Point D, respectively. When water isfurther added to the organic layer of the composition designated withPoint C to obtain a composition designated with Point E, the organiclayer is separated into two layers of an organic layer and an aqueouslayer, whose compositions are designated with Point F and Point G,respectively. If the content of inorganic salts in the organic layer ofthe composition designated with Point F reduces satisfactorily to adesired degree, the washing step is completed. If the washing isincomplete, an additional separation operation is carried out in asimilar manner.

In the present invention, the content of inorganic salts is controlledto be not more than 1% by weight, preferably not more than 0.5% byweight, more preferably not more than 0.1% by weight, based on theweight of the long chain N-acyl acidic amino acid. In the case where thecontent of the inorganic salts in a salt of the long chain N-acyl acidicamino acid is more than 1% by weight based on the weight of the longchain N-acyl acidic amino acid, there results precipitation or turbidityat a low temperature, when the salt of the long chain N-acyl acidicamino acid is incorporated into a liquid detergent.

In the washing step of the process in accordance with the presentinvention, it is recommended to concentrate the tertiary butanol as muchas possible to realize the separation, because the time before reachingseparation equilibrium can be shortened by increasing the concentrationof tertiary butanol within said separation region.

In the washing step in the process in accordance with the presentinvention, the washing temperature is from 35 to 80° C., preferably from40 to 70° C. When the temperature is lower than 35° C., the time beforereaching a separation equilibrium may be prolonged, or a remarkableamount of the inorganic salts remains in the organic layer even at astage of the equilibrium, or no separation occurs depending upon a kindof the long chain N-acyl acidic amino acid or its concentration in theliquid. A boiling point of the azeotropic composition of water/butanolis about 80° C. under atmospheric pressure, and at a temperatureexceeding 80° C., boiling occurs, and as a result it becomes necessaryto carry out the separation under increased pressure. This isdisadvantageous, because a specific apparatus is required.

As made clear from the relation between the long chain N-acyl acidicamino acid and the mixed solvent of water and tertiary butanol,according to the washing step in accordance with the present invention,it is possible to reduce the inorganic salt impurities to a desireddegree also with respect to a long chain N-acyl acidic amino acidcontaining impurities such as inorganic salts, which is producedaccording to a process other than that in accordance with the presentinvention.

As to a solvent distillation removal step in the process in accordancewith the present invention, in removing the hydrophilic organic solventfrom the long chain N-acyl acidic amino acid-containing organic layer, apart of the carboxyl group of the long chain N-acyl acidic amino acid isneutralized before distillation removal of the solvent (neutralizationsolvent distillation removal) or not (non-neutralization solventdistillation removal).

First of all, an illustration is given for the neutralization solventdistillation removal step. According to the process, the hydrophilicorganic solvent is distilled off in the presence of a salt of the longchain N-acyl acidic amino acid.

An alkali salt thereof is not particularly limited. Examples thereof aresalts of alkali metals such as sodium, potassium and lithium, salts ofalkaline earth metals such as calcium and magnesium, aluminum salts,zinc salts, ammonium salts, salts of organic amines such asmonoethanolamine, diethanolamine, triethanolamine andtriisopropanolamine, and salts of basic amino acids such as arginine andlysine.

In order to convert the long chain N-acyl acidic amino acid into itsorganic amine salts or its alkali metal salts, for example, it is onlyneeded to add an alkali or its aqueous solution. In converting into asalt of the long chain N-acyl acidic amino acid, it is recommended toadd the alkali so as to convert not less than {fraction (1/20)} of thecarboxyl group content of the long chain N-acyl acidic amino acid intoits alkali salt. When the proportion of the alkali salt is less than{fraction (1/20)} of the carboxyl group content, the addition effect ofthe alkali is slight and as a result, flowability of the mixed liquidcannot be improved. It is preferred to make the proportion of the alkalisalt at least {fraction (1/10)} or more of the carboxyl group content.It is more preferred to make the proportion of the alkali salt at least⅓ or more of the carboxyl group content.

In the neutralization solvent distillation removal step in accordancewith the present invention, a temperature of the mixed liquid at thetime of distillation is controlled as not to exceed 90° C. When itexceeds 90° C., there is an accelerated thermal hydrolysis reaction ofthe long chain N-acyl acidic amino acid or its salt, and the resultingproduct has inferior quality. Preferably, the temperature is controlledas not to exceed 80° C. More preferably, it is controlled as not toexceed 70° C. In view of controlling the liquid temperature under such acondition, with respect to distillation pressure, it is recommended touse reduced pressure while keeping it at a fixed degree.

Under such conditions, the distillation removal of the hydrophilicorganic solvent can be attained while substantially prohibiting the freeacid from producing.

Here, a pressure-boiling point curve in the system of long chain N-acylacidic amino acid/hydrophilic organic solvent is consistent with apressure-boiling point curve in the system of hydrophilic organicsolvent/water. The long chain N-acyl acidic amino acid is not concernedentirely in the pressure-boiling point curve, and therefore, when atemperature of the mixed liquid is determined, an operation pressure canbe determined from the pressure-boiling point curve in the system ofhydrophilic organic solvent/water.

In the process in accordance with the present invention, water is alsolost with the hydrophilic organic solvent during the distillationremoval, and therefore, as the case may be, there is required a meansfor preventing the long chain N-acyl acidic amino acid fromextraordinarily condensing. Such a means, for example, can be tointermittently or continuously supply water to the solution during thedistillation removal, wherein water includes cool water, hot water andsteam. In the case where the process in accordance with the presentinvention is carried out in a stirring vessel, such a means of blowingsteam is effective from a viewpoint of heat supply, because steam makesgood use of latent heat.

One of important factors in the neutralization solvent distillationremoval in accordance with the present invention is to maintain a solidconcentration in the liquid from 5 to 50% by weight during distillation,for example, according to the means mentioned above. When the solidconcentration is higher than 50% by weight, there is the possibility ofhigh viscosity of the liquid or solidification. When the solidconcentration is lower than 5% by weight, the concentration of thehydrophilic organic solvent is lowered to decrease a distillationefficiency. Moreover, a further concentration is disadvantageouslyrequired in the case where the final product requires a solidconcentration higher than that. It is preferable to maintain the solidconcentration from 20 to 40% by weight. It is more preferable tomaintain the solid concentration from 25 to 35% by weight.

Secondly, an illustration is given for the non-neutralization solventdistillation removal step. According to the process, the hydrophilicorganic solvent is distillation-removed without neutralization of thelong chain N-acyl acidic amino acid.

In the non-neutralization solvent distillation removal step inaccordance with the present invention, it is important to maintain aweight ratio between the long chain N-acyl acidic amino acid and waterwithin a range of from 35/65 to 65/35, provided that a composition ofthe hydrophilic organic solvent in the solution is not more than 5% byweight, and to maintain a solution temperature from 75 to 100° C.

A temperature of the mixed liquid at the time of distillation iscontrolled not to exceed 90° C. When it exceeds 90° C., there is anaccelerated thermal hydrolysis reaction of the long chain N-acyl acidicamino acid or its salt, and the resulting product deteriorates inquality. Preferably, the temperature is controlled as not to exceed 80°C. More preferably, it is controlled not to exceed 70° C. With respectto distillation pressure, it is recommended to carry out distillationunder a fixed degree of reduced pressure, in view of controlling theliquid temperature.

When water decreases during distillation to an amount smaller than 65/35in terms of the weight ratio between the long chain N-acyl acidic aminoacid and water, provided that a composition of the hydrophilic organicsolvent in the solution is not more than 5% by weight, the solutioneasily becomes paste. However, when water increases to an amount largerthan 35/65 in terms of the weight ratio between the long chain N-acylacidic amino acid and water, the solution easily becomes agar. In anycase, flowability of the liquid is lost. Although the reason is notclear, such a tendency is remarkable when the long chain N-acyl acidicamino acid having an acyl group is derived from the foregoing mixedfatty acid, namely an acyl group having a distribution of its carbonatoms.

In the non-neutralization solvent distillation removal step inaccordance with the present invention, water is also lost with thehydrophilic organic solvent during the distillation removal, andtherefore, as the case may be, there is required a means for keeping theweight ratio of long chain N-acyl acidic amino acid/water within a rangeof from 35/65 to 65/35. As a means for keeping the weight ratio withinthe above-mentioned range, for example, it is permitted tointermittently or continuously supply water to the solution during thedistillation removal. In the case where the process in accordance withthe present invention is carried out in a stirring vessel, such a meansof blowing steam is effective from a viewpoint of heat supply, becausethe steam makes good use of latent heat.

By carrying out the solvent removal step as mentioned above, thedistillation removal of the hydrophilic organic solvent can be attainedwhile substantially prohibiting the free fatty acid from producing.

In view of a liquid state at the time of solvent removal, it ispreferred to adopt the neutralization solvent distillation removal step,because the distillation removal of the solvent from the neutralizedliquid minimizes any thermal history.

For carrying out the neutralization and non-neutralization solventdistillation removal steps in accordance with the present invention moreefficiently from an industrial point of view, the following process iseffective.

In carrying out the present invention to distillation-remove thehydrophilic solvent from the mixed liquid of the mixed solvent of waterand the hydrophilic organic solvent, in which the long chain N-acylacidic amino acid is contained, it is effective to adopt an evaporationtechnique using a spray evaporator, wherein the mixed liquid is sprayedinto an evaporation vessel as a vapor-liquid mixed-phase flow, therebyevaporating the hydrophilic organic solvent, as disclosed in, forexample, JP-A 5-49801.

According to this technique, the liquid taken out from the lower part ofthe evaporation vessel is circulated to a heat exchanger with the aid ofa pump, and thereafter the liquid is superheated to a predetermineddegree and is sprayed into the evaporation vessel through a lineprovided to the upper part of the evaporation vessel, therebyevaporating the solvent. Characteristic features of the manner are asfollows.

1) At a vapor phase portion of the evaporation vessel, there is(are)provided one or several line end(s) of an almost cylindrical form towardthe liquid surface, which line end(s) is(are) connected to the lineprovided to the upper part of the evaporation vessel.

2) By controlling both a flow rate of the liquid in the heat exchangerand a degree of excess heat at an outlet of the heat exchanger, thesuperheated liquid sent from the heat exchanger is evaporated to formthe vapor-liquid mixed-phase flow before reaching the line end.

3) The remaining excess heat in the droplet sprayed from the line end isreleased before reaching the liquid phase inside of the evaporationvessel.

The flow form of the vapor-liquid mixed-phase flow is classified asshown in the flow constitutional diagram of vertical vapor-liquidtwo-phase flow in, for example, No.5 revised edition, pages 272 and 273of Kagaku Kogaku Binran (Chemical Engineering Handbook).

When a liquid capable of bubbling is distilled in the above-mentionedmanner, the vapor-liquid mixed-phase flow at the line end is formed intoan intermittent flow or a circulating flow. In practice, the flow formcan be adjusted by controlling both a linear velocity of the liquid atthe line end and a temperature difference (degree of excess heat)between a liquid temperature at the outlet of superheater and a boilingtemperature of the liquid under operation pressure in the evaporationcan.

In addition, according to the manner of using such a spray evaporator,it is possible to remove the high boiling aldol condensation products toa degree of no influence, which condensation products are produced whenthe acylation reaction step is carried out in the mixed solvent ofacetone/water, and which condensation products remaining in goods are sofar difficult to be removed.

In carrying out the solvent distillation removal in accordance with thepresent invention for distillation-removing the hydrophilic organicsolvent from the mixed liquid of water and the hydrophilic organicsolvent, in which the long chain N-acyl acidic amino acid is contained,a thin-film type evaporator can also be used.

The thin-film type evaporator can be exemplified by a falling thin-filmtype evaporator, wherein a liquid is allowed to flow down in aliquid-film form and heated, thereby evaporating a solvent, and a vaporand a condensed liquid are separated from each other in an evaporationvessel, a centrifugal thin-film type evaporator, wherein a liquid isspread on a heating surface with the aid of centrifugal power, therebyforming a thin-film, and a stirring thin-film type evaporator, wherein aliquid thin-film is formed on a heating surface by contacting theheating surface with a stirring blade.

In the long chain N-acyl acidic amino acid or a salt thereof inaccordance with the present invention, it is permitted to remove thehydrophilic organic solvent so as not to affect the odor of the product.In the solvent distillation removal step, a content of tertiary butanolis made to be from 0.1 to 750 ppm by weight, more preferably from 0.1 to300 ppm by weight, much more preferably from 0.1 to 150 ppm by weightbased on the weight of the N-acyl acidic amino acid.

The present invention relates to a long chain N-acyl acidic amino acidor a salt thereof, and an illustration thereof is given as follows.

By carrying out the process in accordance with the present invention,substantially no free fatty acid is produced in the production step ofthe long chain N-acyl acidic amino acid in accordance with the presentinvention, or if any, a quantity thereof can be restrained to bemarkedly small. In addition, the obtained long chain N-acyl acidic aminoacid has substantially no odor and a very small content of inorganicsalts, and therefore is in a high purity and remarkably useful forindustries.

In the long chain N-acyl acidic amino acid or a salt thereof inaccordance with the present invention, a content of the inorganic saltsis not more than 1% by weight based on the weight of the long chainN-acyl acidic amino acid, and a content of tertiary butanol is from 0.1to 750 ppm by weight based on the weight of the long chain N-acyl acidicamino acid.

When the inorganic salts exceeds 1% by weight based on the weight oflong chain N-acyl acidic amino acid, precipitation and turbidity occurat a low temperature when an aqueous solution of a salt of the longchain N-acyl acidic amino acid or a cosmetic composition prepared byincorporating a salt of the long chain N-acyl acidic amino acid into aliquid detergent. The content of the inorganic salts is preferably notmore than 0.5% by weight, more preferably not more than 0.1% by weight.

When tertiary butanol is less than 0.1 ppm by weight based on the weightof the long chain N-acyl acidic amino acid, the masking effect is notsufficient. Whereas, when it is more than that, the masking effect canbe observed, but there is also created a problem from the odor oftertiary butanol.

Such a long chain N-acyl acidic amino acid or a salt thereof can beobtained through at least the washing step in the above-mentionedproduction step.

As another embodiment of the present invention, in the long chain N-acylacidic amino acid or a salt thereof, the content of the inorganic saltsis not more than 1% by weight based on the weight of the long chainN-acyl acidic amino acid, and a content of the free fatty acid is notmore than 3.0% by weight based on the weight of the long chain N-acylacidic amino acid. The long chain N-acyl acidic amino acid or a saltthereof having a content of the free fatty acid of not more than 3.0% byweight based on the weight of long chain N-acyl acidic amino acid isunknown as far as the present inventors know. When the free fatty acidexceeds 3.0% by weight based on the weight of long chain N-acyl acidicamino acid, precipitation and turbidity occur at a low temperature whenan aqueous solution of a salt of the long chain N-acyl acidic amino acidor a cosmetic composition prepared by incorporating a salt of the longchain N-acyl acidic amino acid into a liquid detergent. The content ofthe free fatty acid is preferably not more than 2.5% by weight, morepreferably not more than 2.0% by weight. Such a long chain N-acyl acidicamino acid or a salt thereof can be obtained through at least theacylation reaction step, the washing step and the solvent distillationremoval step in the above-mentioned production step.

As a further embodiment of the present invention, in the long chainN-acyl acidic amino acid or a salt thereof, the content of the inorganicsalts is not more than 1% by weight based on the weight of the longchain N-acyl acidic amino acid, the content of tertiary butanol is from0.1 to 750 ppm by weight based on the weight of the long chain N-acylacidic amino acid, and the content of the free fatty acid is not morethan 3.0% by weight based on the weight of the long chain N-acyl acidicamino acid. Such a long chain N-acyl acidic amino acid or a salt thereofcan be obtained through at least the acylation reaction step, thewashing step and the solvent distillation removal step in theabove-mentioned production step.

The above-mentioned long chain N-acyl acidic amino acid in accordancewith the present invention, wherein a content of impurities such asodoriferous substances originated from the hydrophilic organic solvent,the inorganic salts and the free fatty acid is limited to a fixed degreeor less, can exhibit a remarkably superior performance when compared toa conventional one.

With respect to typical uses of the long chain N-acyl acidic amino acid,for example, there are enumerated materials for industrial detergent andtreatment agent, materials for household (clothes, kitchen and house)detergent and materials for cosmetic products. It can be said that theuses as materials for cosmetic products are particularly effective,because such uses make the best use of low irritating property, which isa characteristic feature of the long chain N-acyl acidic amino acid orits salt.

The cosmetic products in the present invention are genericallyquasi-drugs and cosmetics described in Pharmaceutical Affairs Law.Specific examples of the quasi-drugs are refrigerant troches, underarmdeodorants, baby powders, hair tonics, depilatory agents, hair dyes,permanent wave products, bath products, medicated cosmetics andmedicated toothpastes or powders. Specific examples of the cosmetics arewash cosmetics such as toilet soap, face wash (cream; paste form,liquid; gel form, granule; powder form, aerosol), shampoo and hairrinse, hair cosmetics such as hair dye, hair treatment agent (creamform, mist form, oil form, gel form and other forms, and split haircoating agents), hair set agent (hair oil, set lotion, curler lotion,pomade, stick pomade, bintuke (sidelocks) oil, hair spray, hair mist,hair liquid, hair foam, hair gel, water grease), foundation cosmeticssuch as general cream, milky lotion (cleansing cream, cold cream,vanishing cream, hand cream), mustache shaving cream (after-shavingcream, shaving cream), toilet water (hand lotion, general lotion), Eaude Cologne, mustache shaving lotion (after-shaving lotion, shavinglotion), cosmetic oil and pack, makeup cosmetics such as toilet powder(cream powder, solid powder, face powder, talcum powder, paste powder,baby powder, body powder and liquid face-paint), powder, foundation(cream form, liquid form and solid), lipstick, eye-brow pencil,eye-cream and eye-shadow mascara, perfumery such as general perfume,paste perfume and powder perfume, sunburn or sunscreen cosmetics such assunburn or sunscreen cream, sunburn or sunscreen lotion and sunburn orsunscreen oil, nail cosmetics such as nail cream, enamel and enamelremover, eye liner cosmetics, lip cosmetics such as lipstick and lipcream, oral cosmetics such as toothpaste or powder, and bath cosmeticssuch as bath salt and bath oil. Especially, the product of the presentinvention is extensively used for the above-mentioned wash cosmetics,hair cosmetics and foundation cosmetics, and in particular most suitablyused in the wash cosmetics.

In addition, the product of the present invention can be used incombination with various kinds of materials usually used in cosmeticgoods. Specific examples thereof are anionic surface active agents suchas fatty acid salt (soap), alkyl sulfate (AS), polyoxyethylene alkylether sulfate (AES), α-olefin sulfonate (AOS), alkylbenzene sulfonate,alkylnaphthalene sulfonate, alkyl sulfonate (SAS), dialkylsulfosuccinate, α-sulfonated fatty acid salt, N-acylaminate, salt ofN-acyl-N-methyltaurine, sulfated fatty acid, polyoxyethylenestyrene-modified phenyl ether sulfate, alkylphosphate, polyoxyethylenealkyl ether phosphate, polyoxyethylene alkylphenyl ether phosphate andformalin condensate of naphthalenesulfonate, amphoteric surface activeagents such as alkylbetaine, alkylamidobetaine, alkylsulfobetaine andimidazolynium betaine, nonionic surface active agents such as fatty acidalkylolamide, alkylamine oxide, polyoxyethylene alkyl ether (AE),polyoxyethylene alkylphenyl ether, polyoxyethylene polystyrylphenyether, polyoxyethylene polyoxypropylene glycol, polyoxyethylenepolyoxypropylenealkyl ether, polyhydric alcohol fatty acid partialester, polyoxyethylene polyhydric alcohol fatty acid partial ester,polyoxyethylene fatty acid ester, polyglycerol fatty acid ester,polyoxyethylene hardened caster oil, polyoxyethylene alkylamine andtriethanolamine fatty acid partial ester, cationic surface active agentssuch as primary to tertiary aliphatic amine salt, alkyl chlorideammonium salt, tetraalkyl ammonium salt, trialkylbenzyl ammonium salt,alkylpyridinium salt, alkylhydroxyethylimidazolynium salt anddialkylmorpholinium salt, high molecular weight surface active agentssuch as sodium alginate, starch derivative and tragacanth gum, naturalsurface active agents such as lecithin, lanolin, cholesterol andsaponin, fats and oils such as avocado oil, almond oil, olive oil, cacaooil, sesame oil, safflower oil, soybean oil, tsubaki oil, persic oil,caster oil, mink oil, cotton seed oil, Japan tallow, coconut oil, eggyolk oil, palm oil, palm kernel oil and synthetic triglyceride,hydrocarbons such as liquid paraffin, vaseline, ceresine,micro-crystalline wax and isoparaffin, wax such as beeswax, whale wax,hydrous lanolin, carnauba wax, candelilla wax and its derivative, higherfatty acids such as lauric acid, myristic acid, palmitic acid, stearicacid, isostearic acid, oleic acid, behenic acid, undecylenic acid,lanolin fatty acid, hard lanolin fatty acid and soft lanolin fatty acid,higher alcohols such as lauryl alcohol, cetanol, cetostearic alcohol,stearyl alcohol, oleyl alcohol, behenyl alcohol, lanolin alcohol,hydrogenated lanolin alcohol, hexyldecanol and octyldodecanol, esteroils such as isopropyl myristate and butyl stearate, volatile andnonvolatile oils such as metal soap and silicones including straightsilicone oil and modified silicone oil, humectants such as polyolsincluding glycerol, 1,3-butanediol, propanediol and polyethylene glycol,trimethylglycine, sorbitol, pyrrolidone carbonates, lactates andhyaluronates, water soluble and oil soluble polymers such ashydroxyethyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulosehydroxypropyltrimethylammonium chloride ether, methyl cellulose, ethylcellulose, hydroxypropyl cellulose, methyl hydroxypropyl cellulose,soluble starch, carboxymethyl starch, methyl starch, propylene glycolaluginate, polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl methylether, carboxyvinyl polymer, polyacrylate, guar gum, locust bean gum,quince seed, carrageenan, galactan, gum arabic, pectin, mannan, starch,xanthane gum, dextran, succinoglucan, curdlan, hyaluronic acid, gelatin,casein, albumin, collagen, methoxyethylene maleic anhydride copolymer,amphoteric methacrylate copolymer, polydimethyl chloridemethylenepiperidium, polyacrylate copolymer, polyvinyl acetate,nitrocellulose and silicone resin, thickeners and frothers such aspolyethylene glycol fatty acid ester, polyoxyethylene fatty acid estermethylglycoxide and tetradecene sulfonate, sequestering agents such asethylenediaminetetraacetic acid and its salt,hydroxyethylenediaminetriacetic acid and its salt, phosphoric acid,ascorbic acid, succinic acid, gluconic acid, polyphosphate andmetaphosphate, antiseptics such as paraoxybenzoate, benzoic acid and itssalt and phenoxyethanol, buffer agents such as citric acid, malic acid,adipic acid, glutamic acid and aspartic acid, dandruff and itch removerssuch as trichlorocarbanide, salicylic acid, zinc pyrithion andisopropylmethylphenol, ultraviolet ray absorbers such as benzophenonederivative, p-aminobenzoic acid derivative, p-aminocinnamic acidderivative and salicylic acid derivative, whitening agents such asarbutin, kojic acid, ascorbic acid and derivatives thereof, bloodcirculation facilitating agents such as Japanese chirata extract,cepharanthine, vitamin E and its derivative and γ-oryzanol, localstimuli such as tincture of Japanese chillies, tincture of ginger,tincture of cantharis and benzyl nicotinate, eutrophy agents such asvarious vitamins and amino acids, female hormone drugs, hair bulbactivators, anti-inflammatory agents such as glycyrrhetinic acid,glycyrrhetenic acid derivatives, allantoin, azulene, aminocaproic acidand hydrocortisone, astringents such as zinc oxide, zinc sulfate,allantoin hydroxy aluminum, aluminum chloride, zinc sulfophenoxide andtannic acid, cooling agents such as menthol and camphor, antihistamines,silicone substances such as high molecular silicone and cyclic silicone,tocopherols, antioxidants such as BHA, BHT, gallic acid and NDGA, andpurified water.

Particularly, the combination use with fatty acid diethanolamide,polyoxyethylene dioleic acid methylglucoxide, distearic acidpolyethylene glycol, tetradecene sulfonate, myristates andmyristyldimethylamine is useful from a viewpoint of increasing viscosityand foaming power, and the combination use with each amphoteric surfaceactive agent is remarkably useful from a viewpoint of further lesseningthe irritative property.

The present invention is illustrated in more detail with reference toExamples and others, but the present invention is by no means limitedthereto.

Analysis means and the like used in Examples of the present inventionand others are as follows.

(a) Determination of Inorganic Salt

Respective ions were measured using an inductively coupled plasmaemission analysis apparatus, IRIS/AP (manufactured by Thermo JarrellAsh), provided that a chlorine ion was ion-chromatographically measuredunder conditions of a column of DIONEX AS4SC, a guard column of AG4ASC,a suppressor of AMMS, an eluent of a mixed solution of 3 mmol/L Na₂CO₃and 1 mmol/L NaHCO₃, and a regenerant of 0.05N H₂SO₄.

In the Examples, the content of the inorganic salts is expressed interms of a numerical value based on the weight of the long chain N-acylacidic amino acid.

(b) Determination of Long Chain N-acyl Acidic Amino Acid and Free FattyAcid

This was determined according to high speed liquid chromatography (HPLC)using an ODS column, an eluent of methanol/water/phosphoric acid, anultraviolet detector and a differential refractometric detector.

In the Examples, all of the free fatty acid contents were expressed interms of % by weight based on the weight of long chain N-acyl acidicamino acid.

(c) Determination of Solid Content

Solid content was measured according to weight loss on drying at 105° C.for 3 hours. The solid content is defined as follows.

Solid content (% by weight)=weight after drying/weight before drying×100

(d) Determination of Tertiary Butanol

Tertiary butanol was determined using a gas chromatograph (GC-14A,manufactured by Shimadzu Corporation), a hydrogen flame ionizationdetector, and a glass column of a 3 mm inner diameter, which was packedwith a liquid phase of PEG20M 20% and a carrier of 60 to 80 meshChromosorbW AW-DMCS, in a manner such that at an injection temperatureof 200° C., a column temperature was held at 120° C. for 0 to 10minutes, thereafter raised to 200° C. at 30° C./min and held at 200° C.for 15 minutes.

The tertiary butanol content in Examples is based on the weight of thelong chain N-acyl acidic amino acid.

(e) Organoleptic Odor Test

An evaluation of an odor was carried out by 4 men and 1 woman, who wereall healthy, with respect to an aqueous solution of a salt of a longchain N-acyl acidic amino acid or a shampoo composition prepared byusing said aqueous solution of a salt of a long chain N-acyl acidicamino acid. In evaluating, the liquid to be tested was placed in a glassscrew pipe (35 mm diameter×78 mm height) and the temperature thereof washeld at room temperature and 80° C., respectively. In the evaluationresults of Examples, the case where nobody was aware of any odor such asan odor of fatty acid or that of tertiary butanol is marked with ◯ thecase where any only one person among fives was aware of such an odor ismarked with X

(f) Evaluation of Low Temperature Stability

An aqueous solution of a triethanolamine salt having a solid content of30% by weight in an amount of 10 ml was allowed to cool to a temperatureof not higher than −18° C., and the temperature of either turbidity orwhite precipitation (solidifying point) was observed.

The case where neither turbidity nor precipitation was observed evenwhen the liquid temperature reached −10° C. is marked with ◯, and thecase where either turbidity or precipitation was observed when theliquid temperature reached −10° C. or higher is marked with X.

The result of this test is highly correlative to a low temperaturestability of a cosmetic composition prepared by incorporating thematerial into a liquid detergent or the like.

(g) Evaluation of Low Temperature Stability of Shampoo Composition

A shampoo composition was prepared according to the blendingcompositions shown in Table 2, and held at 5° C. The occurrence ofturbidity was observed at 1 day, 1 week, 1 month, 3 months, and 6months, respectively.

The present invention is illustrated in detail in the Examples but isnot limited by the examples.

(h) Determination of Carboxyl Group Content

About 0.3 g of a sample was accurately weighed and dissolved inethanol/water, and a phenolphthalein indicator was added thereto,followed by titration with an ethanolic potassium hydroxide solution.

REFERENCE EXAMPLES 1 TO 7

The separation region in the mixed system of long chain N-acyl acidicamino acid/tertiary butanol/water, which is the principle ofpurification of the long chain N-acyl acidic amino acid in the washingstep of the present invention, was measured by varying the mixing ratioof the above-mentioned components as are shown in Table 1. Data ofrespective compositions relating to an organic layer and an aqueouslayer separated from the system of N-cocoyl-L-glutamic acid/tertiarybutanol/water are shown. The temperature was 40° C.

REFERENCE EXAMPLES 8 AND 9

The data of Table 1 was taken in a manner similar to that of ReferenceExamples 1 to 7, as an example to show a separation region in the mixedsystem of long chain N-acyl acidic amino acid/tertiary butanol/water inthe washing step. Data of respective compositions relating to an organiclayer and an aqueous layer separated from the system ofN-cocoyl-L-glutamic acid/tertiary butanol/water are shown. Thetemperature was 65° C.

EXAMPLE 1 Acylation Step

To a mixed solution of 1,444 g (7.72 mol) of monosodium L-glutamatemonohydrate, 3,070 g of pure water and 1,235 g of 25% by weight sodiumhydroxide aqueous solution (sodium hydroxide 7.72 mol), 1647 ml of 88%by volume tertiary butanol aqueous solution was added, and 1,760 g (7.56mol, free fatty acid content 2% by weight) of cocoyl chloride wasdropwise added under a stirring power of 0.5 kW/m³ over 2.5 hours, whilecooling the resulting solution and adjusting to pH 12 with use of 25% byweight sodium hydroxide.

Acid-precipitation Separation Step

Stirring was further continued for 30 minutes, and thereafter the pH ofthe liquid was adjusted to 2 by dropwise adding 75% sulfuric acid, andthe temperature was kept at 65° C. After completion of the dropwiseaddition, stirring was finished, and the liquid was allowed to stand at65° C. for 20 minutes, thereby separating into an organic layer and anaqueous layer. The organic layer was obtained. A composition of theorganic layer obtained is shown in Table 2.

Washing Step

Washing One Time

To the separated organic layer, tertiary butanol and water were added toobtain a mixed liquid of N-cocoyl-L-glutamic acid/tertiary butanol/waterin a proportion of 33/25/42(% by weight, respectively), and the mixedliquid was stirred at 65° C. for 20 minutes. After finishing thestirring, the mixed liquid was allowed to stand at 65° C. for 20minutes, thereby separating into an organic layer and an aqueous layer.A composition of the organic layer obtained therefrom and a content ofthe remaining inorganic salt are shown in Table 2.

Solvent Distillation Removal Step

Triethanolamine was added to the organic layer separated and obtained soas to convert 50% of the carboxyl group of the N-cocoyl-L-glutamic acidin the organic layer to its salt, and purified water was added theretoso as to make a solid content of 30% by weight. The resulting liquid wasmixed under stirring.

Thereafter, using a 10 L glass vessel, vacuum distillation was conductedunder a pressure of 327 mmHg, while adding purified water to maintain asolid content to 30% by weight. 12 Hours after starting thedistillation, the liquid temperature reached 78° C., and then thedistillation was finished, thereby obtaining an aqueous solution oftriethanolamine N-cocoyl-L-glutamate. The aqueous solution was found tohave a solid content of 30% by weight, an N-cocoyl-L-glutamic acid yieldof 96.5% (in terms of acid), a tertiary butanol concentration of 60 ppmby weight, and a free acid content of 2.3% by weight.

The results are summarized in Table 2 and Table 3.

EXAMPLE 2

Example 1 was repeated, except that the temperature and standing time inthe acid-precipitation step were changed to 50° C. and 25 minutes,respectively, and the temperature and standing time in the washing stepwere changed to 50° C. and 30 minutes, respectively. After theseparation, an organic layer was obtained through a further separation.

Further, after adding potassium hydroxide to the organic layer obtainedthrough a further separation so as to convert 75% of the carboxyl groupof the N-cocoyl-L-glutamic acid in the organic layer to its salt, andfurther adding pure water thereto so as to make a solid content 30% byweight, the resulting liquid was mixed by stirring. Thereafter, thesolvent distillation removal step was conducted under conditions shownin Table 2.

Twelve hours after starting the distillation, the liquid temperaturereached 52° C., and then the distillation was finished to obtain anaqueous solution of potassium N-cocoyl-L-glutamate.

The results are summarized in Table 2 and Table 3.

EXAMPLE 3

Example 1 was repeated up to the washing step to obtain an organiclayer. To the separated organic layer, tertiary butanol and water wereadded to obtain a mixed liquid of N-cocoyl-L-glutamic acid/tertiarybutanol/water in a proportion of 29/18/53(% by weight, respectively),and the mixed liquid was stirred at 65° C. for 20 minutes. Afterfinishing the stirring, the mixed liquid was allowed to stand at 65° C.for 20 minutes, thereby separating into an organic layer and an aqueouslayer. After said separation, the organic layer was obtained through afurther separation.

After adding 25% sodium hydroxide aqueous solution to the organic layerobtained through a further separation so as to convert 75% of thecarboxyl group of the N-cocoyl-L-glutamic acid in the organic layer toits salt, and further adding pure water thereto so as to make a solidcontent 25% by weight, the resulting liquid was mixed under stirring.Thereafter, the solvent distillation removal step was conducted underconditions as shown in Table 2.

Twelve hours after starting the distillation, the liquid temperaturereached 68° C., and then the distillation was finished to obtain anaqueous solution of sodium N-cocoyl-L-glutamate.

The results are summarized in Table 2 and Table 3.

EXAMPLE 4

Example 3 was repeated up to the washing, except that the washing stepwas conducted two times, thereby obtaining an organic layer. To theseparated organic layer, tertiary butanol and water were added to obtaina mixed liquid of N-cocoyl-L-glutamic acid/tertiary butanol/water in aproportion of 19/27/54(% by weight, respectively), and the mixed liquidwas stirred at 65° C. for 20 minutes. After finishing the stirring, themixed liquid was allowed to stand at 65° C. for 20 minutes, therebyseparating into an organic layer and an aqueous layer. After saidseparation, the organic layer was obtained through a further separation.

To the organic layer obtained through a further separation,triethanolamine was added so as to convert 50% of the carboxyl group ofthe N-cocoyl-L-glutamic acid in the organic layer to its salt, andfurther pure water was added thereto so as to make a solid content 30%by weight. The resulting liquid was mixed under stirring.

Thereafter, using a spray evaporator, the neutralization solventdistillation removal step was conducted.

A spray evaporating apparatus is shown in FIG. 2. The apparatus iscomposed of (1) evaporation can (inner diameter 300 mm, height 700 mm),(2) liquid-circulating pump, (3) heat exchanger, (4) nozzle (innerdiameter of a line end 4 mm) for spraying a heated vapor-liquidmixed-phase flow into the evaporation can, (5) condenser for condensingevaporated gas, and (6) tank of distilled liquid. In FIG. 2, TI and FIstand for a temperature indicator and flow indicator, respectively.

The operation of the apparatus is generally explained. The liquid iscirculated from the lower part of the evaporator with the pump, and sentto the heat exchanger. The liquid going out of the heat exchanger issuperheated, and coming near the nozzle end, gradually evaporates toform a vapor-liquid mixed-phase. It is noted that the distillation canbe carried out under a non-bubble condition even when a liquid capableof bubbling is used, when a flow rate of the circulated liquid (a linearvelocity at the nozzle end) and a degree of excess heat (differencebetween a temperature of the liquid entering into the heat exchanger andthat of the liquid going out of the heat exchanger) are controlled so asto make an intermittent flow as the flow form at this time.

In the present Example, vacuum distillation was conducted underconditions of pressure of 163 mmHg, a linear velocity of the liquid atthe nozzle end of about 1.5 m/sec, and a liquid excess heat of about 20°C., while adding pure water so as to keep a solid content of 30% byweight at the time of distillation. 3.5 Hour-after starting thedistillation, the liquid temperature reached 62° C., and then thedistillation was finished to obtain an aqueous solution oftriethanolamine N-cocoyl-L-glutamate.

The results are summarized in Table 2 and Table 3.

EXAMPLE 5

Example 3 was repeated up to the washing step, except that the washingstep was conducted two times. To the organic layer obtained through afurther separation, potassium hydroxide was added so as to convert 75%of the carboxyl group of the N-cocoyl-L-glutamic acid in the organiclayer to its salt, and pure water was added thereto so as to make asolid content of 28% by weight. The resulting liquid was mixed understirring. Thereafter, the neutralization solvent distillation removalstep was carried out as follows. Using the same apparatus as in Example4, the operation of Example 4 was repeated, except that the pressurecondition was changed to 83 mmHg. 3.5 Hours after starting thedistillation, the liquid temperature reached 46° C., and then thedistillation was finished to obtain an aqueous solution of potassiumN-cocoyl-L-glutamate.

The results are summarized in Table 2 and Table 3.

EXAMPLE 6

Example 3 was repeated up to the washing step, except that the washingstep was conducted two times. To the organic layer obtained through afurther separation, 25% sodium hydroxide aqueous solution was added soas to convert 75% of the carboxyl group of the N-cocoyl-L-glutamic acidin the organic layer to its salt, and further pure water was addedthereto so as to make a solid content of 25% by weight. The resultingliquid was mixed under stirring. Thereafter, the neutralization solventdistillation removal step was carried out as follows.

Using the same apparatus as in Example 4, the operation of Example 4 wasrepeated, except that the pressure condition was changed to 254 mmHg.3.5 Hours after starting the distillation, the liquid temperaturereached 72° C., and then the distillation was finished to obtain anaqueous solution of sodium N-cocoyl-L-glutamate.

The results are summarized in Table 2 and Table 3.

EXAMPLE 7

Example 1 was repeated up to the washing step, except that cocoylchloride was replaced by lauroyl chloride. To the organic layer obtainedthrough a further separation, triethanolamine was added so as to convert50% of the carboxyl group of the N-lauroyl-L-glutamic acid in theorganic layer to its salt, and pure water was added thereto so as tomake a solid content of 30% by weight. The resulting liquid was mixedunder stirring. Thereafter, the neutralization solvent distillationremoval step was carried out as follows.

Using the same apparatus as in Example 4, the operation of Example 4 wasrepeated, except that the pressure condition was changed to 149 mmHg.Four hours after starting the distillation, the liquid temperaturereached 60° C., and then the distillation was finished to obtain anaqueous solution of triethanolamine N-lauroyl-L-glutamate.

The results are summarized in Table 2 and Table 3.

EXAMPLE 8

Example 3 was repeated up to the washing step, except that the washingstep was conducted two times, and thereafter the solvent distillationremoval step was conducted as follows.

Using the same apparatus as in Example 4, the operation of Example 4 wasrepeated, except that the inner diameter of the line end in the spraynozzle of the spray evaporating apparatus was changed to 10 mm, and thepressure condition was changed to 265 mmHg.

Two hours after starting the distillation, the liquid was sampled, and aweight ratio between N-cocoyl-L-glutamic acid and water and a tertiarybutanol concentration in the liquid were found to be 55/45 and 4.2% byweight(in-liquid concentration), respectively, and at that time, theliquid temperature was 68° C. Further, four hours after starting thedistillation, a weight ratio between N-cocoyl-L-glutamic acid and waterand a tertiary butanol concentration in the liquid were found to be53/47 and 5 ppm by weight(in-liquid concentration), respectively, and atthat time, the liquid temperature reached 73° C. Then, the distillationwas finished to obtain a mixed liquid containing 53% by weight ofN-cocoyl-L-glutamic acid. The mixed liquid was dried to obtain a whitesolid of N-cocoyl-L-glutamic acid.

The results are summarized in Table 2 and Table 3.

EXAMPLE 9

Example 3 was repeated up to the washing step, and thereafter thesolvent distillation removal step was conducted as follows.

Using the same apparatus as in Example 4, the operation of Example 4 wasrepeated, except that the inner diameter of line end in the spray nozzleof the spray evaporating apparatus was changed to 10 mm, and thepressure condition was changed to 356 mmHg. Two hours after starting thedistillation, the liquid was sampled, and a weight ratio betweenN-cocoyl-L-glutamic acid and water and a tertiary butanol concentrationin the liquid were found to be 40/60 and 2.0% by weight(in-liquidconcentration), respectively, and at that time, the liquid temperaturewas 75° C. Four hours after starting the distillation, a weight ratiobetween N-cocoyl-L-glutamic acid and water and a tertiary butanolconcentration in the liquid were found to be 41/59 and 6 ppm byweight(in-liquid concentration), respectively, and at that time, theliquid temperature reached 80° C. Then, the distillation was finished toobtain a mixed liquid containing 41% by weight of N-cocoyl-L-glutamicacid. The mixed liquid was dried to obtain a white solid ofN-cocoyl-L-glutamic acid.

The results are summarized in Table 2 and Table 3.

EXAMPLE 10

Example 3 was repeated up to the washing step, and thereafter thesolvent distillation removal step was conducted as follows.

Using the same apparatus as in Example 4, the operation of Example 4 wasrepeated, except that the inner diameter of the line end in the spraynozzle of the spray evaporating apparatus was changed to 10 mm, and thepressure condition was changed to 468 mmHg. Two hours after starting thedistillation, the liquid was sampled, and a weight ratio betweenN-cocoyl-L-glutamic acid and water and a tertiary butanol concentrationin the liquid were found to be 60/40 and 2.5% by weight (in liquidconcentration), respectively, and at that time, the liquid temperaturewas 81° C. Four hours after starting the distillation, the weight ratiobetween N-cocoyl-L-glutamic acid and water and a tertiary butanolconcentration in the liquid were found to be 62/38 and 6 ppm by weight(in-liquid concentration), respectively, and at that time, the liquidtemperature reached 87° C. Then, the distillation was finished to obtaina mixed liquid containing 62% by weight of N-cocoyl-L-glutamic acid. Themixed liquid was dried to obtain a white solid of N-cocoyl-L-glutamicacid.

The results are summarized in Table 2 and Table 3.

EXAMPLE 11

Example 1 was repeated up to the washing step, except that cocoylchloride in the acylation reaction step was changed to lauroyl chloride,and the temperature in the washing step was changed to 50° C.Thereafter, the solvent distillation removal step was conducted asfollows.

Using the same apparatus as in Example 4, the operation of Example 4 wasrepeated, except that the inner diameter of line end in the spray nozzleof the spray evaporating apparatus was changed to 10 mm, and thepressure condition was changed to 234 mmHg. Two hours after starting thedistillation, the liquid was sampled, and a weight ratio betweenN-lauroyl-L-glutamic acid and water and a tertiary butanol concentrationin the liquid were found to be 51/49 and 3.5% by weight(in-liquidconcentration), respectively, and at that time, the liquid temperaturewas 64° C. Four hours after starting the distillation, a weight ratiobetween N-lauroyl-L-glutamic acid and water and a tertiary butanolconcentration in the liquid were found to be 50/50 and 5 ppm byweight(in-liquid concentration), respectively, and at that time, theliquid temperature reached 70° C. Then, the distillation was finished toobtain a mixed liquid containing 50% by weight of N-lauroyl-L-glutamicacid. The mixed liquid was dried to obtain a white solid ofN-lauroyl-L-glutamic acid.

The results are summarized in Table 2 and Table 3.

EXAMPLE 12

Example 1 was repeated up to the washing step, except that sodiumL-glutamate monohydrate and its amount in the acylation reaction stepwere changed to L-aspartic acid and 1028 g (7.72 mol), and thetemperatures in the acid-precipitation separation step and the washingstep were changed to 50° C., respectively. Thereafter the solventdistillation removal step was conducted as follows.

Using the same apparatus as in Example 4, the operation of Example 4 wasrepeated, except that the inner diameter of the line end in the spraynozzle of the spray evaporating apparatus was changed to 10 mm, and thepressure condition was changed to 265 mmHg.

The solvent distillation removal step was carried out as follows.

Two hours after starting the distillation, the liquid was sampled, and aweight ratio between N-cocoyl-L-aspartic acid and water and a tertiarybutanol concentration in the liquid were found to be 54/46 and 3.6% byweight(in-liquid concentration), respectively, and at that time, theliquid temperature was 69° C. Further, four hours after starting thedistillation, a weight ratio between N-cocoyl-L-aspartic acid and waterand a tertiary butanol concentration in the liquid were found to be54/46 and 10 ppm by weight(in-liquid concentration), respectively, andat that time, the liquid temperature reached 73° C. Then, thedistillation was finished to obtain a mixed liquid containing 54% byweight of N-cocoyl-L-aspartic acid. The mixed liquid was dried to obtaina white solid of N-cocoyl-L-aspartic acid.

The results are summarized in Table 2 and Table 3.

EXAMPLE 13

An acylation reaction step was carried out in the same manner as inExample 1, except that tertiary butanol and the amount of pure water inthe acylation reaction step in Example 1 were changed to acetone, and2,405 g, respectively, and acetone was used in an amount of 2,312 ml. Tothe resulting reaction mixture, 20 L of water was added, and 75%sulfuric acid was added thereto to adjust the liquid to pH 1. The crudecrystal of N-cocoyl-L-glutamic acid precipitated was separated byfiltration and dried. The obtained N-cocoyl-L-glutamic acid was found tocontain sodium chloride and sodium sulfate as the inorganic salts inamounts of 1.7% by weight and 1.2% by weight, respectively, based on theweight of N-cocoyl-L-glutamic acid. In addition, the odor thatoriginated from acetone condensation products was severe. Further, theobtained N-cocoyl-L-glutamic acid was adjusted to the same mixed liquidcomposition as in the washing step of Example 1, that isN-cocoyl-L-glutamic acid/tertiary butanol/water=33/25/42 (% by weight,respectively). The resulting liquid was stirred at 65° C. for 20minutes, and then allowed to stand at 65° C. for 20 minutes, therebyseparating into an organic layer and an aqueous layer.

Thereafter, using the resulting mixed liquid, the solvent distillationremoval step was carried out as follows.

Using the same apparatus as in Example 4, the operation of Example 4 wasrepeated, except that the inner diameter of the line end in the spraynozzle of the spray evaporating apparatus was changed to 10 mm, and thepressure condition was changed to 265 mmHg. Two hours after starting thedistillation, the liquid was sampled, and a weight ratio betweenN-cocoyl-L-glutamic acid and water and a tertiary butanol concentrationin the liquid were found to be 53/47 and 4.1% by weight (in liquidconcentration), respectively, and at that time, the liquid temperaturewas 68° C. Four hours after starting the distillation, the weight ratiobetween N-cocoyl-L-glutamic acid and water and a tertiary butanolconcentration in the liquid were found to be 53/47 and 5 ppm by weight(in-liquid concentration), respectively, and at that time, the liquidtemperature reached 73° C. Then, the distillation was finished to obtaina mixed liquid containing 53% by weight of N-cocoyl-L-glutamic acid. Themixed liquid was dried to obtain a white solid of N-cocoyl-L-glutamicacid. The obtained crystal had almost no odor that originated from theacetone condensation products.

The results are summarized in Table 2 and Table 3.

COMPARATIVE EXAMPLE 1

Example 1 was repeated up to the acid-precipitation step, except thatthe amount of cocoyl chloride was changed to 1,976 g (8.49 mol). To theobtained organic layer, tertiary butanol and water were added to obtaina mixed liquid having a composition of N-cocoyl-L-glutamic acid/tertiarybutanol/water=28/58/14 (% by weight, respectively). The mixed liquid wasstirred at 65° C. for 20 minutes. After finishing the stirring, themixed liquid was allowed to stand at 65° C. for 60 minutes, but noseparation of the liquid was found.

The mixed liquid was subjected to solvent distillation removal under thesame conditions as those in the solvent distillation removal step ofExample 1. 12 Hours after starting the distillation, the liquidtemperature reached 78° C., and then the distillation was finished,thereby obtaining an aqueous solution of triethanolamineN-cocoyl-L-glutamate. The product was found to contain the free fattyacid and inorganic salts in each large amount.

The results are summarized in Table 2 and Table 3.

COMPARATIVE EXAMPLE 2

Example 1 was repeated up to the acid-precipitation step, except thattertiary butanol and the amount of pure water in the acylation reactionstep were changed to acetone and 2,405 g, respectively, acetone was usedin an amount of 2,312 ml, and the temperature in the acid-precipitationseparation step was changed to 50° C. To the obtained organic layer,acetone and water were added to obtain a mixed liquid having acomposition of N-cocoyl-L-glutamic acid/acetone/water=33/25/42 (% byweight, respectively). The mixed liquid was stirred at 50° C. for 20minutes, and thereafter allowed to stand for 60 minutes, but noseparation of the liquid was found.

The mixed liquid was subjected to solvent distillation removal underconditions similar to those in the solvent distillation removal step ofExample 1, except that pressure was changed to atmospheric pressure. 15Hour-after starting the distillation, the liquid temperature reached100° C., and then the distillation was finished, thereby obtaining anaqueous solution of triethanolamine N-cocoyl-L-glutamate having a solidcontent of 30% by weight. The product was found to contain the freefatty acid and inorganic salts in each large amount, and there was awareof an odor originated from the acetone condensation products.

The results are summarized in Table 2 and Table 3.

COMPARATIVE EXAMPLE 3

Example 1 was repeated up to the acid-precipitation step. To theresulting organic layer, a 25% sodium hydroxide aqueous solution wasadded so as to convert 75% of the carboxyl group of N-cocoyl-L-glutamicacid to its salt, and pure water was added thereto so as to make a solidcontent of 25% by weight. The resulting mixed liquid was treated in thesame manner as in Example 1, except that the solvent distillationremoval step was carried out as follows.

Vacuum distillation was conducted under pressure of 187 mmHg withoutaddition of pure water.

As the concentration proceeded, the liquid increased its viscosity andresulted in solidification in a gel form, and therefore the distillationwas discontinued. At this time, a solid concentration was found to be55% by weight, and tertiary butanol remained in an amount of 5% byweight based on the weight of N-cocoyl-L-glutamic acid.

The results are summarized in Table 2 and Table 3.

COMPARATIVE EXAMPLE 4

Example 1 was repeated up to the acid-precipitation separation step.Using a 10 L glass vessel, the obtained organic layer was heated undervacuum to distillation-remove tertiary butanol and water, during whichno water was added. On the way, the liquid bubbled, and therefore thedistillation was continued while controlling the pressure within a rangeof from 40 mmHg to atmospheric pressure. 15 Hour-after starting thedistillation, the temperature reached 105° C. and then the distillationwas finished.

To the resulting liquid, triethanolamine was added so as to convert 50%of the carboxyl group of N-cocoyl-L-glutamic acid to its salt, andfurther pure water was added thereto so as to make a solid content 30%by weight. The liquid was mixed under stirring to obtain an aqueoussolution of triethanolamine N-cocoyl-L-glutamate. A yield (as acid) ofN-cocoyl-L-glutamic acid, a tertiary butanol concentration and a freefatty acid content were found to be 92.3%, 80 ppm by weight and 6.5% byweight, respectively.

The results are summarized in Table 2 and Table 3.

COMPARATIVE EXAMPLE 5

Example 1 was repeated up to the acid-precipitation separation step,except that cocoyl chloride was changed to lauroyl chloride. Using a 10L glass vessel, the obtained organic layer was heated under vacuum todistillation-remove tertiary butanol and water, during which no waterwas added. During distillation, the liquid bubbled, and therefore thedistillation was continued while controlling the pressure within a rangeof from 40 mmHg to atmospheric pressure. Fifteen hours after startingthe distillation, the temperature reached 110° C., and then thedistillation was finished.

To the resulting liquid, triethanolamine was added so as to convert 50%of the carboxyl group of N-lauroyl-L-glutamic acid to its salt, andfurther pure water was added thereto so as to make a solid content 30%by weight. The liquid was mixed under stirring to obtain an aqueoussolution of triethanolamine N-lauroyl-L-glutamate. A yield (as acid) ofN-lauroyl-L-glutamic acid, a tertiary butanol concentration and a freefatty acid content were found to be 90.5%, 60 ppm by weight and 8.3% byweight, respectively.

The results are summarized in Table 2 and Table 3.

COMPARATIVE EXAMPLE 6

Example 1 was repeated up to the acid-precipitation separation step,thereby obtaining an organic layer through a further separation. Themixed liquid was subjected to solvent distillation removal underconditions similar to those in the solvent distillation removal step ofExample 1, except that pressure was changed to 588 mmHg. Twelve hoursafter starting the distillation, the liquid temperature reached 93° C.,and then the distillation was finished, thereby obtaining an aqueoussolution of triethanolamine N-cocoyl-L-glutamate having a solid contentof 30% by weight.

A yield (as acid) of N-cocoyl-L-glutamic acid, a tertiary butanolconcentration and a free fatty acid content were found to be 95.3%, 60ppm by weight and 3.5% by weight, respectively.

EXAMPLE 14

Using the aqueous solutions of long chain N-acyl acidic amino acid saltsobtained in the above Examples and Comparative Examples, theorganoleptic odor test mentioned in the above item (e) was carried outat room temperature and 80° C. Incidentally, with respect to the theN-cocoyl-L-glutamic acid and N-lauroyl-L-glutamic acid obtained inExamples 8 to 13, before using them, triethanolamine was added theretoto convert 50% of the carboxyl group to each salt, and further purewater was added thereto to make a solid content 30% by weight, therebyobtaining each aqueous solution of triethanolamine salt having a solidcontent of 30% by weight.

The results are also shown in Table 3.

EXAMPLE 15

Using the aqueous solutions of long chain N-acyl acidic amino acidsobtained in Example 1, Example 4, Example 7, Comparative Example 1,Comparative Example 2, Comparative Example 4 and Comparative Example 5,the low temperature stability test of technical compound mentioned inthe above item (f) was carried out. Further, using solutions obtained inExample 8, Example 10, Example 11 and Example 13, the same test wascarried out, provided that before using them, triethanolamine was addedthereto to convert 50% of the carboxyl group of long chain N-acyl acidicamino acid in the liquid to each salt, and further pure water was addedthereto to make a solid content 30% by weight, thereby obtaining eachaqueous solution of triethanolamine salt having a solid content of 30%by weight.

The results are shown in Table 4.

EXAMPLE 16

Using the material obtained in Example 1, Example 4, Comparative Example2 and Comparative Example 6, each shampoo composite liquid having acomposition as shown in Table 5 was prepared in the following manner.

Cationic cellulose was dissolved in a portion of purified water, whilebeing heated. The remaining components were mixed in a separate portionat 80° C. to be made uniform. Both portions were combined and mixed tobe made uniform, then cooled and filled in a vessel.

The thus obtained shampoo composite liquid was kept at 5° C., and oneday thereafter, one week thereafter, one month thereafter, three monthsthereafter and six months thereafter, the occurrence of turbidity wasobserved.

As a result, each shampoo composite liquid containing the product ofeither Example 1 or Example 4 was found to be clear even six monthsthereafter. Whereas, in each shampoo composite liquid containing theproduct of either Comparative Example 2 or Comparative Example 6, agreat turbidity was observed one day thereafter, so that propertiesessential to the shampoos were markedly impaired.

In addition, in using the shampoo composite liquids, the organolepticodor test mentioned in the above item (e) was carried out at roomtemperature and 80° C.

As a result, the odor results relating to each shampoo composite liquidcontaining products of Example 1, Example 4 or Comparative Example 6revealed ◯ (no odor observed), and on the other hand, the resultrelating to Comparative Example 2 revealed X (one person in fiveobserves an odor).

INDUSTRIAL APPLICABILITY

The process in accordance with the present invention is a simple processfor producing a long chain N-acyl acidic amino acid, which can be putinto practice with industrial stability. Further, the long chain N-acylacidic amino acid or a salt thereof produced according to the presentinvention has substantially no odor, and when incorporated into a liquiddetergent or a cosmetic composition, it is capable of giving a longchain N-acyl acidic amino acid-containing cosmetic composition, whichcauses neither turbidity nor precipitation even for long storage timesparticularly at low temperatures.

TABLE 1 Mixed liquid Organic layer Aqueous layer Cocoyl Cocoyl Cocoylglutamic glutamic glutamic Reference acid TBA H₂O acid TBA H₂O acid TBAH₂O Example wt % wt % wt % wt % wt % wt % wt % wt % wt % 1 34 26 40 4532 24 0.2 14 86 2 38 25 37 43 27 30 0.4 14 86 3 38 25 37 43 27 30 0.4 1486 4 28 14 58 43 15 42 0.4 12 88 5 14 35 51 17 39 44 0.4 19 81 6 29 3932 31 40 29 0.4 17 82 7 10 30 60 21 44 35 0.4 18 81 8 32 21 46 46 27 270.2  8 92 9 31 28 41 40 31 29 0.5  7 93

TABLE 2 Acid-precipitation separation step Composition of organic layerafter acid-precipitation Acylation step Acyl Organic Temperature aminoacid TBA Water Example Acidic amino acid Fatty acid halide solvent ° C.wt % wt % wt % Example 1 L-Glutamic acid Cocoyl chloride TBA 65 62 24 14Example 2 L-Glutamic acid Cocoyl chloride TBA 50 50 37 13 Example 3L-Glutamic acid Cocoyl chloride TBA 65 62 24 14 Example 4 L-Glutamicacid Cocoyl chloride TBA 65 62 24 14 Example 5 L-Glutamic acid Cocoylchloride TBA 65 62 24 14 Example 6 L-Glutamic acid Cocoyl chloride TBA65 62 24 14 Example 7 L-Glutamic acid Lauroyl chloride TBA 65 62 24 14Example 8 L-Glutamic acid Cocoyl chloride TBA 65 62 24 14 Example 9L-Glutamic acid Cocoyl chloride TBA 65 62 24 14 Example 10 L-Glutamicacid Cocoyl chloride TBA 65 62 24 14 Example 11 L-Glutamic acid Lauroylchloride TBA 50 51 39 10 Example 12 L-Aspartic acid Lauroyl chloride TBA50 52 37 11 Example 13 L-Glutamic acid Cocoyl chloride AcetoneCrystallization and filtration were conducted Comparative L-Glutamicacid Cocoyl chloride TBA 65 62 24 14 Example 1 Comparative L-Glutamicacid Cocoyl chloride Acetone 50 50 Acetone 10 Example 2 40 ComparativeL-Glutamic acid Cocoyl chloride TBA 65 62 24 14 Example 3 ComparativeL-Glutamic acid Cocoyl chloride TBA 65 62 24 14 Example 4 ComparativeL-Glutamic acid Lauroyl chloride TBA 65 49 37 14 Example 5 ComparativeL-Glutamic acid Cocoyl chloride TBA 65 62 24 14 Example 6 Washing stepComposition of mixed Composition of organic liquid after washing layerafter separation Acyl Acyl Temperature amino acid TBA Water amino acidTBA Water Example ° C. wt % wt % wt % wt % wt % wt % Example 1 65 31 2247 45 28 27 Example 2 65 32 22 46 45 27 28 Example 3 Two times 65 30 2545 44 32 24 Example 4 Three times 65 19 27 54 34 35 31 Example 5 Twotimes 65 30 25 45 44 32 24 Example 6 Two times 65 30 25 45 44 32 24Example 7 65 31 22 47 45 28 27 Example 8 Two times 65 30 25 45 44 32 24Example 9 Two times 65 30 25 45 44 32 24 Example 10 Two times 65 30 2545 44 32 24 Example 11 65 33 25 42 44 30 26 Example 12 50 25 20 55 40 2733 Example 13 65 33 25 42 43 27 30 Comparative 65 25 58 14 No separationExample 1 Comparative 50 33 Acetone 42 No separation Example 2 25Comparative No conducted Example 3 Comparative No conducted Example 4Comparative No conducted Example 5 Comparative No conducted Example 6Solvent distillation step Condition of distillation Maximum liquidNeutralization Non-neutralization temperature and and Kind of alkali &Maximum distillation distillation neutralization degree Pressure liquidSolid Acyl amino Distillation Neutralization Pressure temperaturecontent acid/water time Example Alkali degree mmHg ° C. wt % wt ratio HrExample 1 TEA 0.5  327 78 30 — 12 Example 2 KOH 0.75 102 52 28 — 12Example 3 NaOH 0.75 214 68 25 — 12 Example 4 TEA 0.5  163 62 30 — 3.5Example 5 KOH 0.75  83 48 28 — 3.5 Example 6 NaOH 0.75 254 72 25 — 3.5Example 7 TEA 0.5  163 62 30 — 3.5 Example 8 None None 265 73 — 53/47 4Example 9 None None 356 80 — 41/59 4 Example 10 None None 468 87 — 62/384 Example 11 None None 234 70 — 50/50 4 Example 12 None None 265 73 —54/46 4 Example 13 None None 265 73 — 53/47 4 Comparative TEA 0.5  32778 30 — 12 Example 1 Comparative TEA 0.5  Atmospheric 100  30 — 15Example 2 pressure Comparative NaOH 0.75 187 65 55 — — Example 3Comparative None None Atmospheric 105  — 100/0  15 Example 4 pressureComparative None None Atmospheric 110  — 100/0  15 Example 5 pressureComparative TEA 0.5  588 93 30 — 12 Example 6

TABLE 3 Long chain N-acyl acidic amino acid or its salt Impurities inacyl amino acid Odor of Acyl Amount of Free acyl aminate amino acidremaining Inorganic salts fatty aqueous solution Yield TBA Na₂SO₄ NaClacid Evaluation Example % wt ppm wt % wt % wt % result Example 1 96.5 600.044 0.063 2.3 ◯ Example 2 97.0 62 0.12 0.09 1.7 ◯ Example 3 96.8 700.006 0.009 1.9 ◯ Example 4 97.1 50 <0.004 <0.001 1.7 ◯ Example 5 97.170 0.006 0.009 1.6 ◯ Example 6 97.0 75 0.006 0.009 1.7 ◯ Example 7 97.051 0.043 0.060 1.7 ◯ Example 8 97.0 50 0.006 0.009 1.8 ◯ Example 9 96.860 0.006 0.009 1.9 ◯ Example 10 96.6 60 0.006 0.009 2.1 ◯ Example 1197.1 65 0.12 0.052 1.8 ◯ Example 12 97.0 65 0.11 0.060 1.8 ◯ Example 1396.8 55 0.19 0.095 1.9 ◯ Comparative 86.5 60 0.64 0.63 12.3  ◯ Example 1Comparative 92.3 Acetone 1.3 1.7 6.5 X Example 2 N.D. Comparative —50000   0.93 0.70 — X Example 3 Comparative 92.3 80 0.64 0.63 6.5 ◯Example 4 Comparative 90.5 60 0.92 0.70 8.3 ◯ Example 5 Comparative 95.360 0.64 0.63 3.5 ◯ Example 6

TABLE 4 Evaluation on 30% triethanolamine aqueous solution Evaluation onFree fatty Solidifying shampoo composite liquid Na₂SO₄ NaCl acid contentpoint State Test liquid (wt %) (wt %) (wt %) (° C.) Evaluation Odor ofliquid Evaluation Example 1 Triethanol N- 0.044 0.063 2.3 −12.0 ◯ ◯Transparent ◯ cocoyl-L- even after glutamate six months aqueous solutionExample 4 Triethanol N- <0.044 <0.001 1.7 −13.0 ◯ ◯ Transparent ◯cocoyl-L- even after glutamate six months aqueous solution Example 7Triethanol N- 0.043 0.060 1.7 −12.5 ◯ — — — lauroyl-L- glutamate aqueoussolution Example 8 Triethanol N- 0.006 0.009 1.8 −12.6 ◯ — — — cocoyl-L-glutamate aqueous solution Example 10 Triethanol N- 0.006 0.009 2.1−12.0 ◯ — — — cocoyl-L- glutamate aqueous solution Example 11 TriethanolN- 0.12 0.052 1.8 −12.3 ◯ — — — lauroyl-L- glutamate aqueous solutionExample 13 Triethanol N- 0.19 0.095 1.9 −12.3 ◯ — — — cocoyl-L-glutamate aqueous solution Comparative Triethanol N- 0.64 0.63 12.3 −7.0X — — — Example 1 cocoyl-L- glutamate aqueous solution ComparativeTriethanol N- 1.3 1.7 6.5 −9.0 X X Turbidity was X Example 2 cocoyl-L-observed one day glutamate after blending aqueous solution ComparativeTriethanol N- 0.64 0.63 6.5 −9.0 X — — — Example 4 cocoyl-L- glutamateaqueous solution Comparative Triethanol N- 0.92 0.7 8.3 −9.0 X — — —Example 5 lauroyl-L- glutamate aqueous solution Comparative TriethanolN- 0.64 0.63 3.5 −10.6 ◯ ◯ Turbidity was X Example 6 cocoyl-L- observedone day glutamate after blending aqueous solution

TABLE 5 Amount blended Composition (wt. part) TriethanolamineN-cocoyl-L- 34.5 glutamate aqueous solution Lauryldimethylaminoaceticacid 12 betaine Coconut oil fatty acid 5 diethanolamide Cationiccellulose 0.6 1,3-Butanediol 0.5 Purified water Balance to make thewhole

What is claimed is:
 1. A process for producing a N-(C₈-C₂₀)-acyl acidicamino acid, comprising a washing step of removing impurities byseparating a mixture of the N-(C₈-C₂₀)-acyl acidic amino acid, which isobtained through the following steps, and which contains inorganic saltsas impurities, and a medium consisting essentially of water and tertiarybutanol into an aqueous layer and an organic layer containing theN-(C₈-C₂₀)-acyl acidic amino acid at a temperature of from 35 to 80°C.: 1) an acylation reaction step of subjecting an acidic amino acid anda long chain fatty acid halide to condensation in a mixed solventconsisting essentially of water and tertiary butanol in the presence ofan alkali, and 2) an acid precipitation separation step of adjusting apH of the obtained reaction liquid to from 1 to 6 with a mineral acid toseparate the mixture into an organic layer and an aqueous layer, therebyobtaining an organic layer containing the N-(C₈-C₂₀)-acyl acidic aminoacid.
 2. The process according to claim 1, wherein the mixture in thewashing step is adjusted to have a N-(C₈-C₂₀)-acyl acidic amino acidconcentration of from 0.001 to 55% by weight, a tertiary butanolconcentration of from 5 to 45% by weight and a water concentration offrom 20 to 99% by weight, thereby causing the separation.
 3. The processaccording to claim 1 or 2, wherein a molar ratio of long chain fattyacid halide/acidic amino acid in the acylation reaction step is not morethan 1.05.
 4. The process according to claim 1 or 2, wherein the pH inthe acid precipitation separation step is from 1 to
 3. 5. The processaccording to claim 1 or 2, wherein the organic layer containing theN-(C₈-C₂₀)-acyl acidic amino acid obtained in the washing step issubjected to removal of an organic solvent by distillation, in which notless than {fraction (1/20)} of carboxyl groups in the N-(C₈-C₂₀)-acylacidic amino acid is converted into its alkali salt, and thedistillation is carried out at a temperature not exceeding 90° C., andwater is added to maintain a solid concentration of the mixed liquid tofrom 5 to 50% by weight.
 6. The process according to claim 1 or 2,wherein the organic layer containing the N-(C₈-C₂₀)-acyl acidic aminoacid obtained in the washing step is subjected to removal of an organicsolvent by distillation, wherein the temperature does not exceed 90° C.,and water is added to maintain a weight ratio between theN-(C₈-C₂₀)-acyl acidic amino acid and water within a range of from 35/65to 65/35, provided that a content of the organic solvent in the mixedliquid is not more than 5% by weight.
 7. The process according to claim1 or 2, wherein in distillation-removing an organic solvent from theorganic layer containing the N-(C₈-C₂₀)-acyl acidic amino acid obtainedin the washing step, the distillation-removal of an organic solvent iscarried out using a spray evaporator, wherein the mixture is formed intoa vapor-liquid mixed-phase, which is then sprayed into an evaporationcan to evaporate the solvent.
 8. A composition, which comprises: aN-(C₈-C₂₀)-acyl acidic amino acid or a salt thereof; an inorganic saltof not more than 1% by weight; and tertiary butanol of from 0.1 to 750ppm by weight, said contents being based on the weight of theN-(C₈-C₂₀)-acyl acidic amino acid.
 9. The composition according to claim8, which has a content of a free fatty acid of not more than 3.0% byweight based on the weight of the N-(C₈-C₂₀)-acyl acidic amino acid. 10.The composition according to claim 8 or 9, which is obtained by areaction between an acidic amino acid and a long chain fatty acid halidein a mixed solvent consisting essentially of tertiary butanol and water.11. The composition according to claim 8 or 9, which is obtainedaccording to a process comprising a washing step of removing aninorganic salt by separating a mixture composed of the N-(C₈-C₂₀)-acylacidic amino acid containing an inorganic salt and a medium consistingessentially of water and tertiary butanol into an aqueous layer and anorganic layer containing the N-(C₈-C₂₀)-acyl acidic amino acid at atemperature of from about 35 to 80° C.
 12. The composition according toclaim 8 or 9, which is obtained through the following steps: 1) anacylation reaction step of subjecting an acidic amino acid and a longchain fatty acid halide to condensation in a mixed solvent consistingessentially of water and tertiary butanol in the presence of an alkali,2) an acid precipitation separation step of adjusting a pH of theobtained reaction liquid to from 1 to 6 with a mineral acid to separateinto an organic layer and an aqueous layer, thereby obtaining an organiclayer containing the N-(C₈-C₂₀)-acyl acidic amino acid, and 3) a washingstep of removing impurities by mixing the obtained organic layer withwater and/or tertiary butanol to separate into an aqueous layer and anorganic layer containing the N-(C₈-C₂₀)-acyl acidic amino acid at atemperature of from 35 to 80° C.
 13. The composition according to claim8 or 9, which is obtained through the following steps: 1) an acylationreaction step of subjecting an acidic amino acid and a long chain fattyacid halide to condensation in a mixed solvent consisting essentially ofwater and tertiary butanol in the presence of an alkali, 2) an acidprecipitation separation step of adjusting a pH of the obtained reactionliquid to from 1 to 6 with a mineral acid to separate into an organiclayer and an aqueous layer, thereby obtaining an organic layercontaining the N-(C₈-C₂₀)-acyl acidic amino acid, 3) a washing step ofremoving impurities by mixing the obtained organic layer with waterand/or tertiary butanol to separate into an aqueous layer and an organiclayer containing the N-(C₈-C₂₀)-acyl acidic amino acid at a temperatureof from 35 to 80° C., and 4) a neutralization and solvent distillationremoval step of subjecting the organic layer containing theN-(C₈-C₂₀)-acyl acidic amino acid obtained in the washing step toremoval of an organic solvent by distillation, in which no less than{fraction (1/20)} of carboxyl groups of the N-(C₈-C₂₀)-acyl acidic aminoacid is converted into its alkali salt, and the distillation is carriedout under conditions that a temperature of a resulting mixed liquid iscontrolled as not to exceed 90° C., and water is added to maintain asolid concentration of the mixed liquid of from 5 to 50% by weight. 14.The composition according to claim 8 or 9, which is obtained through thefollowing steps: 1) an acylation reaction step of subjecting an acidicamino acid and a long chain fatty acid halide to condensation in a mixedsolvent consisting essentially of water and tertiary butanol in thepresence of an alkali, 2) an acid precipitation separation step ofadjusting a pH of the obtained reaction liquid to from 1 to 6 with amineral acid to separate into an organic layer and an aqueous layer,thereby obtaining an organic layer containing the N-(C₈-C₂₀)-acyl acidicamino acid, 3) a washing step of removing impurities by mixing theobtained organic layer with water and/or tertiary butanol to separateinto an aqueous layer and an organic layer containing theN-(C₈-C₂₀)-acyl acidic amino acid at a temperature of from 35 to 80° C.,and 4) a neutralization and solvent distillation removal step ofsubjecting the organic layer containing the N-(C₈-C₂₀)-acyl acidic aminoacid obtained in the washing step to removal of an organic solvent bydistillation, which is carried out under conditions that a temperatureis controlled as not to exceed 90° C., and water is added to maintain aweight ratio between the N-(C₈-C₂₀)-acyl acidic amino acid and waterwithin a range of from 35/65 to 65/35, provided that a content of theorganic solvent in the mixed liquid is not more than 5% by weight.
 15. Aliquid or solid cosmetic composition, which comprises a N-(C₈-C₂₀)-acylacidic amino acid or a salt thereof having a content of an inorganicsalt of not more than 1% by weight and a content of tertiary butanol offrom 0.1 to 750 ppm by weight, said contents being based on the weightof the N-(C₈-C₂₀)-acyl acidic amino acid.
 16. A liquid or solid cosmeticcomposition, which comprises a N-(C₈-C₂₀)-acyl acidic amino acid or asalt thereof having a content of an inorganic salt of not more than 1%by weight and a content of tertiary butanol of from 0.1 to 750 ppm byweight, an a content of a free fatty acid of not more than 3.0% byweight, said contents being based on the weight of the N-(C₈-C₂₀)-acylacidic amino acid.
 17. A detergent composition, which comprises aN-(C₈-C₂₀)-acyl acidic amino acid or a salt thereof having a content ofan inorganic salt of not more than 1% by weight and a content oftertiary butanol of from 0.1 to 750 ppm by weight, said contents beingbased on the weight of the N-(C₈-C₂₀)-acyl acidic amino acid.
 18. Adetergent composition, which comprises a N-(C₈-C₂₀)-acyl acidic aminoacid or a salt thereof having a content of an inorganic salt of not morethan 1% by weight and a content of tertiary butanol of from 0.1 to 750ppm by weight, an a content of a free fatty acid of not more than 3.0%by weight, said contents being based on the weight of theN-(C₈-C₂₀)-acyl acidic amino acid.